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IC 


8997 



Bureau of Mines Information Circular/1985 




Automated Temporary Roof Support 
(ATRS) Systems for Roof 
Bolting Machines 

Proceedings: Bureau of Mines Technology Transfer 
Symposium, Charleston, WV, June 23, 1983 

Compiled by William W. Aljoe 




UNITED STATES DEPARTMENT OF THE INTERIOR g» 



c 



75 



Af/NES 75TH A^ 



Information Circular 8997 ( . 

Automated Temporary Roof Support 
(ATRS) Systems for Roof 
Bolting Machines 

Proceedings: Bureau of Mines Technology Transfer 
Symposium, Charleston, WV, June 23, 1983 



Compiled by William W. Aljoe 



UNITED STATES DEPARTMENT OF THE INTERIOR 
William P. Clark, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 



«D 



W 



O 



Q' 



Library of Congress Cataloging in Publication Data: 



Bureau of Mines Technology Transfer Symposium (1983: 
Charleston, WV) 

Automated temporary roof support (ATRS) systems for roof boltinj 
machines. 

(Information circular ; 8997) 

Includes bibliographical references. 

Supt. of Docs, no.: I 28.27:8997. 

1. Mine roof bolting— Automation. 2. Mining machinery —Automa- 
tion. I. Aljoe, William W. II. Title. III. Series: Information circu- 
lar (United States. Bureau of Mines) ; 8997. 



m29&,«4 [TN289.3] 622s [622'.2] 84-600208 



CONTENTS 

Page 

Abstract 1 

Improved roof control safety with ATRS systems, by M. Terry Hoch and William J. 

Debevec. 2 

Development of waiver guidelines for the use of ATRS systems in West Virginia 

coal mines, by Govindappa Puttaiah and Ashok K. Agrawal 9 

Field test of an ATRS system on a low-coal, single fixed-head roof bolting 

machine (squirmer), by Edward A. Barrett and Thomas E. Marshall 18 

Development of an ATRS system for Fairchild Inc. roof drills, by George Cobb... 27 

Retrofit ATRS systems for roof bolters, by Gary 0. Bledsoe 32 

The Schroeder Frontrunner roof bolter with ATRS system, by Gus Schroeder 39 

Remotely actuated temporary support (RATS) for FMC underground mining 

equipment , by Martin D. Wotring 48 

Roof support systems for Fletcher roof drills, by Douglas R. Hardman . ... 55 

ATRS systems for Lee-Norse roof bolters , by Guido Bucelluni 69 

Long-Airdox ATRS systems for roof bolters, by C. L. Bandy, Jr., and David L. 

Phillips 74 





UNIT OF 


MEASURE 


ABBREVIATIONS USED 


IN 


THIS REPORT 


ft 


foot 




lb/ft 2 




pound per square foot 


f t/min 


foot per 


minute 


pet 




percent 


gal 


gallon 




psi 




pound per square inch 


in 


inch 




s 




second 


lb 


pound 




yr 




year 



AUTOMATED TEMPORARY ROOF SUPPORT (ATRS) SYSTEMS 
FOR ROOF BOLTING MACHINES 

Proceedings: Bureau of Mines Technology Transfer Symposium, 
Charleston, WV, June 23, 1983 

Compiled by William W. Aljoe 1 



ABSTRACT 

This publication contains 10 papers presented at a symposium on ATRS 
systems in Charleston, WV, on June 23, 1983. Included are papers by 
MSHA Technical Support (Roof Control) , West Virginia Institute of Tech- 
nology, the Bureau of Mines, and seven roof bolter manufacturers and/or 
designers of ATRS systems. These papers summarize the most recent de- 
velopments in ATRS technology and can serve as a guide to potential de- 
signers, developers, and users of ATRS systems. 



1 Mining engineer, Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA, 



IMPROVED ROOF CONTROL SAFETY WITH ATRS SYSTEMS 
By M. Terry Hoch 1 and William J. Debevec 2 



The collapse of mine roof has always 
been a major safety problem confronting 
the mining industry. Historically, roof 
falls have caused the death of more coal 
miners than the combined total of all 
other types of accidents. From 1906 
through 1980, 85,026 lives were claimed 
in coal mine underground workings. Roof 
falls were responsible for 44,628 of 
these deaths, or 52 pet of the fatalities 
on record. However, as can be seen in 
figure 1, roof fall fatalities have ex- 
hibited a downward trend. This graph was 
formulated by taking 10-yr increments 



1 



Supervisory mining engineer. 



^Mine safety specialist. 
Bruceton Safety Technology Center, 
Mine Safety and Health Administration, 
Bruceton, PA. 



from 1910-19 through 1970-79, averaging 
the roof fall fatalities occurring in 
those years, and plotting them chronolog- 
ically. Although the number of miners 
working in underground bituminous mines, 
and therefore the number of hours worked, 
has decreased in these years , the per- 
centage reduction in workers and worker- 
hours is far less than the percentage re- 
duction in roof fall fatalities. 

Accident statistics are often deceiv- 
ing unless normalized with exposure 
times. The following material is in- 
tended to place accident information into 
perspective. Figure 2 compares the tons 
mined, the worker-hours involved, and the 
roof fall fatalities for 1970 through 
1982. All of these statistics were re- 
ceived from the Mine Safety and Health 



1,350 



,200 - 



(/> 


1,05 


UJ 




K 




IJ 


900 


< 




r- 




< 
u_ 


750 



-J 600 1- 
< 

o 450 
o 

300 
150 [ 





1910-19 1920-29 1930-39 1940-49 1950-59 1960-69. 1970-79 
FIGURE 1. - Roof fall fatalities - 10-yr average. 



100 




240 



H 220 £ 



3 
o 



■ 200 « 



o 
180 ^ 

Ld 



1970 1972 1974 1976 1978 1980 1982 

FIGURE 2. - Frequency curves. 



350 



325 g 



300 



CD 
O 



275 o 

Q 
O 

rr 
250 cl 



225 



Administration (MSHA) Health and Safety 
Analysis Center (HSAC) in Denver, CO, and 
pertain only to underground bituminous 
coal mines. A high of 84 fatalities was 
registered in 1970 and a low of 31 in 
1980. The 1970 high of 337.9 million 
tons has not been surpassed, although the 
1982 total of 320.9 million tons repre- 
sents the second highest mark in this 13- 
yr study. The drastic decrease in ton- 
nage for 1977 and 1978 was due to work 
stoppages. (Note that the baseline of 
the graph represents 225 million tons.) 
Worker-hours have followed a definite up- 
ward trend with a leveling off in the 
past few years. Since 1970, an increase 
of approximately 40 pet in total worker- 
hours can be seen. With the increase in 



hours worked and the general decrease in 
roof fall fatalities over the past 13 yr, 
a correlation exists suggesting that sig- 
nificant safety advances have been made 
that protect miners from the No. 1 under- 
ground hazard - roof falls. 

This paper discusses one of these ad- 
vances that MSHA believes to be a major 
contributor to this reduction in roof 
fall fatalities and that has a tremendous 
potential for further decreasing fatali- 
ties and injuries in the years to come. 
This advance is the use of automated tem- 
porary roof support (ATRS) systems, which 
provide protection from roof falls and 
are remotely set from beneath permanently 
supported roof. 



1979-81 ROOF FALL FATALITIES: GENERAL OBSERVATIONS 



As a means of justifying our be- 
liefs, let us first take a close look 
at the roof fall fatality records for 
1979, 1980, and 1981. The reason for 
focusing on these years is because a suf- 
ficient description of the statistics is 
available and the use of ATRS systems 
was beginning to accelerate during these 
years. It is estimated that machines 
equipped with ATRS systems increased from 



approximately 1,500 in 1979 to approxi- 
mately 2,500 by June 1, 1983. 

Table 1 summarizes the roof fall fatal- 
ities that occurred in 1979, 1980, and 
1981. The total number of fatalities for 
all types of accidents in underground bi- 
tuminous mines respectively was 105, 94, 
and 112, and the total number of roof 
fall fatalities in these years was 65, 



TABLE 1. - Summary of roof fall 
fatalities 1 



Fatalities 

Underground bituminous 

(total) , 

Roof fall , 

Roof fall (inby 

supports) , 

Percent of roof fall 

fatalities (inby 

supports) 

'HSAC statistics. 



1979 



105 
65 

52 



80 



1980 



94 
32 

22 



69 



1981 



112 
41 

24 



59 



fall fatalities that are directly asso- 
ciated with manual setting of temporary 
supports. This activity is listed as 
"setting, removing, or preparing posts" 
by HSAC. With an ATRS system, this ac- 
tivity would virtually be eliminated and 
would reduce the amount of exposure time 
in which miners would be inby supports. 
As the figures show in table 2, the per- 
centage of fatals related to manually set 
temporary supports compared with total 
roof fall fatals in any year has been 
decreasing. 



32, and 41. A breakdown of these roof 
fall fatalities was made by HSAC, and it 
revealed that a large percentage has oc- 
curred inby permanent supports. Table 1 
illustrates that in 1979, 1980, and 1981 
there were respectively 52, 22, and 24 
roof fall fatalities inby supports. Al- 
though this number is unacceptably high, 
the percentage of roof fall fatalities 
that have occurred inby supports with re- 
spect to total roof fatals has progres- 
sively decreased in this 3-yr period. 
These figures imply that ATRS systems are 
reducing the percentage of roof fall fa- 
talities occurring inby supports. Also, 
significant reductions in the total num- 
ber of fatalities can be assumed as more 
and more mines convert to ATRS systems 
from manually set temporary supports. 

Additional statistics that justify this 
belief are expressed in table 2. This 
figure illustrates the number of roof 



TABLE 2. - Fatality data on manually 
set temporary supports 



Fatalities 


1979 


1980 


1981 


Setting, removing, or 










20 


7 


8 




65 


32 


41 




31 


22 


20 



The point to be brought out by these 
statistics is that no matter what year 
is viewed, the results are the same; the 
occupations that require men to work 
in close proximity to the unsupported 
face are the high-fatality-frequency 
jobs. Assuming that the miners were well 
trained in roof control techniques, it 
can be implied that a reduction in acci- 
dents can be achieved by technological 
advances and by reducing or eliminating 
the amount of exposure time spent in un- 
supported areas through the use of auto- 
mated temporary roof support. 



ATRS IN LIEU OF CANOPIES 



The ATRS systems presently in use are 
an integral part of the roof bolting ma- 
chines or continuous miners equipped with 
integral bolters. They are designed so 
they can be set in the unsupported area 
from a remote position under permanent 
support. As the name implies, they are 
automated and therefore provide a posi- 
tive support to the mine roof and elimi- 
nate the human error involved in setting 
conventional temporary support. 

MSHA, through the Roof Control Division 
of the Bruceton Safety Technology Cen- 
ter in cooperation with our enforcement 



personnel, has pioneered the development 
of ATRS systems for the past 10 yr. 
Working with mining companies, machine 
manufacturers, union representatives, 
State agencies, and independent jobbers 
has produced safe, functional designs. 
In fact, the design of ATRS systems has 
been perfected so that in many mines they 
are accepted in lieu of canopies over the 
drilling controls of roof bolters and 
continuous miners with integral bolters. 
To be approved for use in lieu of cano- 
pies, the system must provide equal or 
greater protection from roof falls to the 
operator as required in CFR 75. 1710-l(f ) . 



The first "in-lieu-of" approval was 
granted in 1976, and since then 191 ap- 
provals have been issued. They involve 
301 mines and approximately 2,000 ma- 
chines. An additional 500 machines in 
the field have an ATRS with a canopy, 
which precludes the necessity for an 
"in-lieu-of" approval. Experience with 
machines currently equipped with ATRS 
systems shows that mine operators are 
realizing a substantial reduction in ac- 
cidents caused by falls of mine roof dur- 
ing the roof bolting cycle. In addition, 
the use of these systems has resulted in 
the reduction of both face bolting time 
and the manual workload for roof bolter 
operators and helpers. 

Currently, there is some confusion be- 
tween approval of an ATRS system to re- 
place manual setting of temporary sup- 
ports and approval for use in lieu of 
canopies. Figure 3 illustrates the dif- 
ference. For a mining company to gain 
approval to use an ATRS system to re- 
place manual setting of temporary sup- 
ports, the company must submit an appli- 
cation through the local MSHA district 
manager. Acceptance is conditional, de- 
pending on a variety of mining circum- 
stances. On the other hand, if the ma- 
chine does not provide a substantial 
canopy, the ATRS system may be accepted 
for use in lieu of a canopy over the 
drilling controls, but approval must be 
granted by the Chief of MSHA's Bruceton 
Safety Technology Center, through the 
Director of Technical Support. 

Based on past performance and in-mine 
investigations, the following general 
criteria have been established to deter- 
mine the acceptability of ATRS systems 
for either approval: 



Approvals 



ATRS 

To replace manually 

setting temporary 

supports 



ATRS 

Acceptance for use 
in lieu of 
a canopy 




MSHA 
district manager 



' MSHA v 

technical support 
chief of safety center 



FIGURE 3. - Approvals. 

1. The necessary ATRS system controls 
should be located so that they can be op- 
erated from under permanent supports. 

2. The ATRS system should be firmly 
placed against the roof before advancing 
inby permanent supports. 

3. All ATRS system hydraulic jacks 
should have check valves. 

4. The ATRS system should be certified 
by a registered, professional engineer to 
withstand a prescribed load. This load 
is dependent on the intended work area. 

5. The distance between the ATRS sys- 
tem and the coal face, rib, or perma- 
nent or temporary supports should be not 
greater than 5 ft. 

6. Inch tram speed should be limited 
to a maximum of 80 ft/min. 



GENERAL DESCRIPTION OF ATRS TYPES 



Current ATRS systems consist of either 
a bar-type or safety-arm-type support for 
roof bolting machines and hydraulic jacks 
equipped with roof contact pads for con- 
tinuous miners with integral bolters. 
Each has advantages and disadvantages de- 
pending on the specific application, but 



in general, they all perform the basic 
function of providing temporary support 
while the roof is being bolted. 

Shown in figure 4 is a side view of the 
safety-arm type. It was developed to 
provide temporary roof support in the 



immediate area of the roof bolt being in- 
stalled. This type consists of a pair of 
steel arms mounted on each drill boom 
with a support structure attached to the 




FIGURE 4. - Safety-arm-type ATRS system. 



top end. The support structures, which 
are of various sizes and configurations, 
are pressurized against the mine roof 
from a remote position by means of hy- 
draulic elevating cylinders that rest 
directly on the mine floor. With the 
safety-arm type, the ATRS system must be 
repositioned remotely for each bolt to be 
installed. 

Figure 5 displays a single-bar system. 
The bar-type ATRS usually consists of ei- 
ther one or two bars equipped with roof 
contact pads mounted atop a hydraulic 
jack that can be pressurized against the 
mine roof from under permanently sup- 
ported roof. This system is generally 
attached to a dual-boom roof bolter. 

Dual-boom roof bolting machines are 
generally easier to equip with an ATRS 
system than single-boom, fixed-head 
"squirmer-type" machines. The lack of an 
operator's compartment and the location 
of the drilling controls at the front 



KEY 
■ Roof bolt 
x Proposed bolt hole 

O Operator's position 
X X 



i i 
i i 



V 



I 

r'-S 

I I 
1 I 



7 




Inch tram -ATRS 

Tram station 



FIGURE 5. - Single-bar ATRS system. 



of the single-head machines account for 
the difficulty. Although some operators 
have been successful in placing canopies 
over a newly attached operator's compart- 
ment, in many cases this hinders the 
roof bolting operations because the can- 
opy restricts roof bolting close to the 
rib. Therefore, several mine operators 
equipped their roof bolters with ATRS 
systems for use in lieu of canopies over 
the drilling controls. Figure 6 is a 
plan view drawing of a fixed-head machine 
with an ATRS. The systems are generally 
modified versions of types adapted to the 
dual-boom roof bolting machines, and some 
have been approved in lieu of canopies 
and as sole or partial means of temporary 
support during the roof bolting cycle. 

Although ATRS systems on single-boom 
bolters for use in lieu of canopies have 
been accepted by MSHA on a mine-to-mine 
basis, their use as the sole means of 
temporary support has been limited. The 
inherent design of the machine requires 
it to be repositioned after each bolt 



,Dnlling controls 



ATRS 
tram controls 



I Hi 

-inch / 




KEY 
■ Roof bolt 
x Proposed bolt hole 
OOperator's position 



FIGURE 6. - Fixed-head machine with ATRS. 



installation. However, improved technol- 
ogy, actual underground work experience, 
design modifications, and changing of 
work procedures have resulted in an 
increase in the use of these ATRS systems 
as temporary support. 

Approvals of ATRS systems on continuous 
miners has been increasing in the past 
few years. By law, canopies are required 
over the drilling controls on continuous 
miners equipped with integral drills. 
However, in many cases these canopies ex- 
tend beyond the machine frame and require 
greater mining widths to accommodate 
them. These wider entries were detrimen- 
tal to good roof control; therefore, in 
some mines operators have equipped their 
machines with ATRS systems which can be 
accepted in lieu of canopies over the 
drilling controls. Figure 7 shows a plan 
view of a continuous miner with ATRS 
jacks. The sequence of operation is as 
follows: 

1. The roof bolt operators remain un- 
der permanent support until mining has 
progressed far enough to install the next 
row of bolts. 

2. The miner operator then positions 
the ATRS supports firmly against the 
roof. 

3. The bolter operators then advance 
to their drilling controls and install 
the roof bolts. 

4. When the bolting is completed, the 
roof bolter operators retreat to a perma- 
nently supported area and the mining cy- 
cle continues. 

It is easy to see that safety and pro- 
duction can be enhanced with the use of 
ATRS systems on continuous miners by roof 
bolting close to the face and reducing 
the number of moves required. 



Front ATRS pads Front ATRS controls 
.(set by miner operator)/ 

^Miner controls 



Operator's 
canopy 




Rear ATRS pads 
(set by bolter) 



Drilling-rear 
ATRS controls 



Roof bolts' 



FIGURE 7. - Continuous miner with ATRS jacks. 



CONCLUSION 



A review of fatality statistics shows 
a general downward trend, particularly 
in the roof control area. MSHA believes 
that a major contributor to this re- 
duction has been the use of ATRS sys- 
tems on roof bolters and continuous 
miners equipped with integral bolters. 
The Roof Control Division of MSHA and our 



enforcement personnel have assisted and 
will continue to assist manufacturers and 
mining companies in the development of 
workable ATRS systems. The outlook is 
very bright for even further reduction 
in accidents and fatalities through the 
use of automated temporary roof support 
systems. 



DEVELOPMENT OF WAIVER GUIDELINES FOR THE USE OF ATRS SYSTEMS 
IN WEST VIRGINIA COAL MINES 



By Govindappa Puttaiah 1 and Ashok K. Agrawal 



INTRODUCTION 



More than 35,000 miners have been 
killed by roof falls in underground coal 
mines in the past 70 yr. As shown in 
figure 1, the yearly toll has been dra- 
matically reduced during the last few 
decades due to improved mining methods. 
However, the fatality figures are still 
unacceptably high, and further reduction 
could be achieved with better roof sup- 
port techniques. 

Table 1 shows that roof falls have his- 
torically accounted for approximately 50 
pet of all underground coal mine fatali- 
ties each year (^). 2 Studies have also 
shown that 60 pet of the roof fall fatal- 
ities occur within 25 ft of the face. Of 



the 211 roof fall fatalities between 1974 
and 1978, 109 occurred inby permanent 
supports and 46 involved miners who were 
manually setting or removing temporary 
posts or jacks. 

Current mining practice requires that 
prior to installing permanent roof sup- 
ports, miners must enter unsupported roof 
areas to manually set temporary supports. 
Such temporary supports provide protec- 
tion during the bolt installation cycle. 
To minimize worker exposure to the unsup- 
ported roof , various Federal agencies , 
mining machinery manufacturers, and min- 
ing companies initiated the development 
of automated roof support (ATRS) systems. 



1 Division of Mining Engineering Tech- 
nology, West Virginia Institute of Tech- 
nology, Montgomery, WV. 

^underlined numbers in parentheses re- 
fer to items in the list of references at 
the end of this report. 



m 

of" 

< 

Ll) 

>- 

(T 
UJ 
Q. 

(/) 

UJ 



2 
< 

u. 



1,000 



800 - 



600 - 



400 - 



200 - 




V- O) 



C\/ <V f*) "O V \f (O <0 (O (O \ \ 



o m o <o o <o o <o O ,<o p ,<o o {o 

0)0)0) 0)0)0)0) O) O) O) O) O) O) O) 

FIGURE 1. - Coal mine fatalities per year 
(1910-79). 



TABLE 1. - Total fatality-roof fall 
fatality record of West Virginia 
coal mines (1960-79) 



Year 


Total 


Roof fall 


pet 1 




fatalities 


fatalities 






115 


66 


57.4 




84 


41 


48.8 




77 


39 


50.6 




126 


55 


43.6 




85 


48 


56.4 




93 


53 


57.0 




81 


40 


49.4 




60 


28 


46.6 




152 


30 


19.7 




69 


27 


39.1 




63 


29 


46.0 




41 


16 


39.0 




48 


13 


27.1 




41 


19 


46.3 




36 


16 


44.4 




34 


12 


35.3 




32 


7 


21.9 


1977 


28 


13 


46.4 


1978 


29 


11 


38.0 




35 


16 


45.7 



1 Roof fall fatalities 
tal fatalities. 



as percent of to- 



10 



These systems can provide protection dur- 
ing the bolting cycle by remotely setting 
the temporary support. Over the past 
decade or so, considerable progress has 
been made in the development of various 
types of ATRS systems. Use of ATRS sys- 
tems in underground coal mines started to 
accelerate during the late 1970' s. Cur- 
rently, many mines are using ATRS systems 
on dual-boom roof bolters with great suc- 
cess; however, use of ATRS systems on 
single-boom bolters is rather limited. 
Studies of roof fall fatalities for 1979 
and 1980 have shown that there were 18 
fewer deaths inby permanent roof support 
in 1980 than in 1979. This may have been 
due in part to the increase in ATRS use 
during 1980. 



create a condition which will cause 
a greater hazard, to people working 
inby the area where permanent sup- 
ports have been installed, than the 
method presently being employed or 
proposed by the operator for tem- 
porarily supporting the roof; or 
where the technology of an auto- 
mated temporary roof support system 
does not exist to allow compliance 
with the requirements set forth in 
Section 5.03 of these rules and 
regulations. In granting a waiver 
as to the use of the automated tem- 
porary roof support system, the Di- 
rector may approve the use of tem- 
porary jacks and posts to be used 
in lieu thereof. 



Convinced of the potential danger due 
to exposure to unsupported roof and the 
advantages of using ATRS systems , the 
six-member Coal Mine Health and Safety 
Board of the West Virginia Department of 
Mines unanimously approved rules and reg- 
ulations governing the use of ATRS in 
West Virginia coal mines. The rules and 
regulations (chapter 22, article 2-A, 
section A, series 21 (1981) of the West 
Virginia Code) became effective on March 
1, 1981. The regulations state in part — 

5.01 (a) Twelve (12) months after the 
effective date of these rules and 
regulations all new and rebuilt, 
roof bolting machines and continu- 
ous mining machines with integral 
roof drills used in a working place 
in a coal mine shall be provided 
with an approved automated tempo- 
rary roof support system: Pro- 
vided, that other methods of tempo- 
rarily supporting the roof may be 
approved by the Director in the 
adopted approved roof control plan. 

5.02 (b) A waiver may be granted, as to 
the use of an automated temporary 
roof support system, by the Direc- 
tor where it has been demonstrated 
by the operator and determined dur- 
ing an investigation by an author- 
ized representative of the Director 
that the use of an automated tem- 
porary roof support system would 



Note that section 5.02 (b) of these 
rules and regulations states that a 
waiver may be granted from the use of the 
ATRS system (1) if it has been demon- 
strated that its use will cause a greater 
hazard, or (2) where the technology of an 
ATRS system does not exist. The above 
rule also charges the Director of the 
West Virginia Department of Mines with 
the responsibility of granting such 
waivers. In order to grant waivers on an 
unbiased and technically sound basis, the 
West Virginia Department of Mines con- 
tracted the Division of Mining Engineer- 
ing Technology at West Virginia Institute 
of Technology to develop and recommend a 
set of waiver guidelines. Keeping in 
mind the waiver criteria set forth in the 
law, the investigators initiated a com- 
prehensive study of existing ATRS systems 
and the problems associated with them. 
The following tasks were performed under 
the study: 

1. Review of literature on ATRS 
technology. 

2. Review of MSHA census on roof bolt- 
ers and ATRS systems in West Virginia. 

3. Visits to ATRS manufacturers and 
rebuild shops. 

4. Visits to underground coal mines 
using the ATRS system. 



11 



5. Discussions with Federal agen- 
cies, coal industry groups, and labor 
associations. 

6. Review of statistical information 
on roof falls. 

7. Review of geological and engineer- 
ing literature on the region's coal mine 
roof strata. 

No attempt is made here to establish 
rigid guidelines; this would tend to 



oversimplify extremely complex relation- 
ships that exist among various ATRS- 
related mining variables. It became evi- 
dent during the study that the procedures 
and criteria to be considered in the 
evaluation of such guidelines must be 
clarified. Thus, the results of this re- 
port include a thorough review of the 
technical status of ATRS systems and the 
identification of various factors that 
need to be evaluated in the consideration 
of an ATRS waiver. 



ROOF BOLTER SURVEY 



Section 5.01 (b) of the ATRS regulation 
requires that, starting March 1, 1984, 
all the existing roof bolting machines 
and continuous mining machines with inte- 
gral roof drills used in a working place 
must be retrofitted with an approved ATRS 
system. Hence, it became necessary that 
a survey of existing roof bolters be con- 
ducted to get an idea of the magnitude of 
retrofitting work involved. 

Table 2 shows the data obtained from a 
roof bolter survey conducted in District 
4 of the Mine Safety and Health Admini- 
stration, which covers mines in southern 
West Virginia. Data were compiled ac- 
cording to roof bolter types (dual boom 
or single boom) , ATRS existence on the 
roof bolter, and manufacturer. The data 
show that 275 of the 290 dual-boom roof 
bolters now in use (95 pet) have some 
type of ATRS system as an integral part 
of the machine. However, 605 of the 698 
single-boom roof bolters (almost 87 pet) 



do not have ATRS systems with the machine 
and may have to be retrofitted. Almost 
all the continuous miners with integral 
roof drills have some type of ATRS sys- 
tem. As shown in table 2, 400 of the 
605 single-boom roof bolters without ATRS 
systems (almost 66 pet) are FMC (Galis) 
models. Fletcher, Long-Airdox, and Lee- 
Norse account for the majority (23 pet) 
of the other single-boom roof bolters 
without ATRS systems. 

No such data were available from MSHA 
District 3, which covers mines in north- 
ern West Virginia. However, interviews 
with MSHA and the West Virginia Depart- 
ment of Mines personnel revealed that 
the use of single-boom bolters in Dis- 
trict 3 is minimal. Therefore, the ex- 
tent of retrofitting work required in 
northern West Virginia should not be as 
great as that required in southern West 
Virginia. 



TABLE 2. - Summary of roof bolters in southern West Virginia 



Manufacturer 


Dual boom 


Single boom 




With ATRS 


Without ATRS 


With ATRS 


Without ATRS 


ACME 


4 

157 

46 

64 

4 







3 
6 

5 
1 







6 
73 
7 
4 
2 

1 



17 




54 




400 
36 




20 


Black Diamond (Wildcat).... 


56 

16 

4 

2 




275 


15 


93 


605 



12 



ATRS SYSTEMS 



MSHA has defined a temporary roof sup- 
port system (TRS) as a device that sup- 
ports a minimum weight of 450 lb/ft 2 
times the area to be supported. Most 
ATRS systems are incorporated into roof 
bolting machines or continuous miners 
equipped with integral roof bolters. The 
positioning controls for the ATRS are 
located so the operator can set the sys- 
tem while remaining under supported roof. 
Thus, an ATRS system must be extended and 
pressurized against the newly exposed 
roof remotely and is intended to replace 
manually installed posts and/or jacks as 
temporary support while the roof is being 
bolted. 

ATRS FOR ROOF BOLTERS 

Various machine manufacturers and ret- 
rofitted, coal mining companies, the 
Bureau of Mines, and MSHA's Roof Control 
Division of the Bruceton Safety Technol- 
ogy Center have been working for over 10 
yr to design and produce safe and func- 
tional ATRS systems for different types 
of roof bolters. These intensive efforts 
have resulted in the development of sev- 
eral workable ATRS systems. 

All currently available ATRS systems 
can be broadly categorized as either in- 
tegral types or satellite types. 

An integral type of ATRS system is one 
in which the system is rigidly attached 
to the roof bolting machine. Integral- 
type ATRS systems are available for most 
existing dual-boom and some single-boom 
roof bolting machines. The three most 
common support mechanisms currently 
available are the ring type, T-bar type, 
and H-bar type. 

Figure 2 shows the ring type (also 
called the safety-arm type) ATRS devel- 
oped to provide temporary roof support 
in the immediate area of the roof while 
the bolt is being installed. This type 
consists of a roof support structure 
(ring) mounted above each drill boom. A 
steel arm, a pair of arms, or hydraulic 
cylinders usually connect the support 



structure to the machine frame and/or the 
mine floor. The support structures and 
steel arms have various sizes and config- 
urations and are pressurized against the 
mine roof from a remote position by the 
hydraulic cylinders. The safety-arm ATRS 
system must be repositioned remotely be- 
fore each bolt is installed. 

Figure 3 shows a T-bar system, which 
usually consists of either one or two 



Drilling 
control? 




7 

ATRS- inch 
control 



Tram 
station 



KEY 

■ Roof bolt 
x Proposed bolt hole 
=0 Operator's position 

FIGURE 2. - Ring-type ATRS system. 




W 



<}- 



1 1 



Front view 
of rocker pad 



KEY 
x Proposed bolt hole 
■ Roof bolt 
O Operators position 



Inch tram and J 
ATRS controls S 



FIGURE 3. - T-bar-type ATRS system. 



13 



bars equipped with roof contact pads 
mounted atop a hydraulic jack that can be 
pressurized against the mine roof from 
under the permanently supported roof. 
This system is generally attached to a 
dual-boom roof bolter. 

Figure 4 shows an H-bar type of system 
used predominantly as a retrofit kit for 
single-boom bolters. The basic support 
and operating mechanisms are similar to 
those of the ring or safety-arm types. 

The satellite type of ATRS system is 
being designed mainly for single-boom 
roof bolters. The Bureau of Mines and 
several industry organizations are inde- 
pendently involved in the development and 
field testing of satellite-type systems 
(fig. 5). The system basically consists 
of a steel beam or steel pads supported 
by double-acting, telescoping hydraulic 




/Operat^j-n 

f Mo u n t i n g plate 



Set left to right 



ATRS protective envelope 




I /"""111 Drill controls Jr=T- 
\ Operator ^^ — -~~~ 



Tram canopy 



cylinders. The ATRS is carried from 
place to place and row to row on the 
drill head but is not an integral part of 
the machine. During bolting, the support 
structure is connected to the machine 
only by hydraulic lines. A detailed de- 
scription of this system is available 
through the Bureau of Mines (2). 

ATRS SYSTEMS FOR CONTINUOUS MINERS 

The ATRS law was written to include 
both roof bolters and continuous miners 
with integral roof bolters. Although 
many roof bolter designs are available, 
only two companies are currently manufac- 
turing continuous miners with on-board 
roof bolters. These machines have hy- 
draulic roof support jacks mounted adja- 
cent to the drilling and bolting modules 
just inby the miner operator's com- 
partment. The jacks can be operated from 
a safe distance under permanently sup- 
ported roof. Since both of these miner- 
bolters already have ATRS systems, no 
further discussion of these machines is 
warranted. 



4th row 



3d row 



Head connects 

to satellite 

TRS for 

positioning 




Tram station 

TRS positioning 

controls 



2d row 



I st row 



Roof bolts 



g \ Operator 
r position 



FIGURE 4. - H.bar=type ATRS system. 



FIGURE 5. - Satellite-type ATRS system. 



14 



NEED FOR ATRS WAIVERS 



As noted earlier, section 5.02 (b) of 
the Rules and Regulations Governing the 
Use of ATRS systems provides that the 
key issues to be considered in seeking 
and granting a waiver are (1) the deter- 
mination that an ATRS system would cre- 
ate a greater hazard than the method 
presently being employed or proposed by 
the operator, and (2) lack of technology 
to allow compliance with the ATRS law. 
Mine geology obviously influences these 
considerations . 

HAZARD POSSIBILITIES DUE TO ATRS 

A greater hazard to miners (i.e., 
roof bolter operator and helpers) may be 
caused by employing an ATRS for the fol- 
lowing reasons: 

Reduced Visibility . — The use of ATRS 
may cause reduced visibility of the roof 
surfaces and the surrounding space in 
general, particularly in thin-seam coal 
mines. The roof bolter operator may have 
difficulty in locating the bolt holes 
within the tolerances permitted by the 
roof control plan. This may result in 
improperly supported roof with the possi- 
bility of roof falls and/or citations. 

Roof or Floor Conditions . — Severe un- 
even roof or floor conditions, especially 
if they are recurring features in the 
mine, may result in insufficient or non- 
uniform contact between ATRS support pads 
and the roof. Under these conditions the 
use of conventional post-type temporary 
supports may provide better contact with 
the roof and greater safety than an ATRS. 

Induced Pressure . — The upward pressure 
created on an unsupported roof while the 
ATRS is being set up may destabilize the 
roof , especially if the immediate roof 
rock has low shear strength or is in- 
tensely fractured. However, since the 
upward force exerted by an ATRS can be 
controlled by the bolter manufacturer and 
the drill operator, this should not be 
considered a criterion for granting a 
waiver. 



Mobility Considerations . — Movement of 
an ATRS, particularly the bar type, in a 
confined space near the face may cause 
hazardous conditions such as knocking 
down temporary posts, initiating rib and 
roof failures by unintentional contact, 
physical damage to face ventilation sys- 
tems , etc. 

LACK OF ATRS TECHNOLOGY 

Roof bolter size and coal seam thick- 
ness are the two main factors that need 
to be considered during the evaluation of 
any ATRS technology. Interviews with the 
manufacturers and retrofitters have re- 
vealed that the size of the roof bolter, 
and not the type, was the major problem 
in the development of a workable ATRS 
system. Because a direct relationship 
exists between the bolter size and coal 
seam thickness , the presence or lack of 
ATRS technology depends on coal seam 
thickness. In this report, a thin seam 
is defined as one that is less than 36 
in; medium, between 36 and 60 in; thick, 
between 60 and 100 in; and very thick, 
over 100 in. 

In general, there are few ATRS systems 
available for thin coal seams. However, 
discussions with manufacturers of roof 
bolters indicate that efforts are being 
made to develop ATRS systems for low 
coal, primarily for new roof bolters. 
However, as shown in table 2, a large 
number of existing single-boom roof bolt- 
ers must be retrofitted with ATRS by 
March 1, 1984. Since most of the re- 
quests for ATRS waivers will be for thin- 
seam roof bolters, careful examination 
must be made of the available retrofit 
technology. 

Some large manufacturers are developing 
retrofit ATRS systems for their existing 
thin-seam roof bolters. Several designs 
are beyond the prototype stage, and oth- 
ers are on the drawing board. These de- 
signs are expected to be available before 
1984 and should be able to meet the needs 
of most existing thin-seam roof bolters. 



15 



A wide variety of ATRS systems are now 
available for roof bolters used in medium 
seams. Therefore, no waivers should be 
granted to medium-seam roof bolters based 
on seam thickness alone. 

Sufficient ATRS technology also exists 
for thick-seam roof bolters; therefore, 
no waivers should be granted. Although 
ATRS technology for very thick coal seams 
(above 100 in) is not as well devel- 
oped as it is for medium and thick seams , 
very thick seam mines are not common in 
West Virginia. Therefore, requests for 



waivers in very thick seams can easily be 
treated on an individual basis. 

MINE GEOLOGY 

The frequency of roof falls is closely 
related to immediate roof conditions (ta- 
bles 3 and 4, figure 6) (3). As shown in 
table 3, shale was the immediate roof 
rock in over 80 pet of roof falls where 
fatalities occurred. Table 4 shows that 
thickness of the shale roof has a signif- 
icant impact on roof stability; as shale 



TABLE 3. - Roof conditions where fatalities occurred 



Rock type 


Good to 
firm 


Fair 


Poor 


Bad 


Total 
cases 


pet 


Shale 


8 
5 




46 
2 

6 


140 

10 



23 


22 
2 
1 
4 


216 

19 

1 

33 


80.29 


Head or top coal 


7.06 

.38 

12.27 




13 


54 


173 


29 


269 


100.00 



TABLE 4. - Comparison of roof fall data by period 





July 1973-June 1978 


July 1978-June 1980 




Mine 
acres 


Roof 
falls 


Falls per 
acre 


Mine 
acres 


Roof 
falls 


Falls per 
acre 


Reduction 
in F/A, ' pet 


Shale roof thick- 
ness, ft: 

to 5 


118.2 
111.8 
76.2 
53.9 
30.1 
13.5 


30 
56 
49 
71 
50 
37 


0.16 
.50 
.64 
1.32 
1.66 
2.74 


246.0 
71.5 
31.8 
56.0 
18.6 
29.8 


10 
17 

9 
11 


11 


0.04 
.24 
.28 
.20 
.0 
.37 


75 


>5 to 10 


52 


>10 to 20 


56 


>20 to 30 


85 


>30 to 40 


100 




86 


Total or average 
Extraction ratio (e): 


473.7 

91.2 

382.5 

77.3 

32.7 

363.7 


293 

84 

209 

9 

5 

279 


.62 
.92 
.55 

.12 
.15 
.77 


453.7 

19.5 

434.2 

242.7 

174.2 

36.8 


58 

8 

50 

12 
34 
12 


.13 
.41 
.12 

.05 
.19 
.33 


80 
55 
79 

58 

227 

57 



' Falls per acre of mine development. 

2 This apparent increase in falls per acre i 
being too low (5 falls was an incomplete sampl 
been 0.45, or midway between 0.12 and 0.77. 
represent an equivalent 57 pet reduction over 



s probably a result of the 0.15 figure 
e) . A more realistic figure would have 
Then the 0.19 figure for 1978-80 would 
the first period. 



16 



roof thickness increased from 5 to 20 ft, 
roof falls per acre increased from 0.16 
to 0.64. 

Local defects such as slickensides , 
pots, slips, loose shale, fractures, and 
faults are associated with a majority of 
roof falls and fatalities (fig. 6). Fur- 
thermore, roof rock properties, especial- 
ly those of shale, are affected by chang- 
ing moisture conditions in the mine. 
Therefore, a thorough evaluation of imme- 
diate roof geology and the mine moisture 
conditions should be made as part of any 
waiver consideration. 




Slickensides, pots, slips 
Loose shale or slate 
Fractures 
Moisture 

Faults 

Disturbance, bumps 
Separations in roof 

20 40 60 
FATAL ACCIDENTS, pet 

FIGURE 6. - Geological conditions contributing 
to fatal roof falls. 



RECOMMENDATIONS 



1. The West Virginia Department of 
Mines should define more precisely what a 
waiver is likely to encompass. Opinions 
of manufacturers, operators, safety and 
training directors, and miners show no 
consensus whatsoever on the extent of an 
ATRS waiver. Some believe that a mine- 
wide waiver may be necessary, while oth- 
ers think that it may be needed for only 
a part of the mine. Still others feel 
that a waiver may be necessary only for a 
particular machine. This confusion as to 
the intent and applicability of the ATRS 
waiver should be resolved before consid- 
ering any waiver request. 

2. The Department of Mines should de- 
fine the term "Waiver" more precisely in 
order to make the distinction between a 
"waiver" and a modification to the exist- 
ing mine roof control plan. Many mines 
will have to change their present roof 
control plans to allow incorporation of 
ATRS systems. 

3. A comprehensive study of all fac- 
tors discussd in this report should 
be conducted upon receipt of a waiver 
application. 

4. All factors should be weighed on 
their merits and considered together and 
no single factor should be the deciding 
criterion, with the possible exception of 
available ATRS technology. 



5. All roof bolter operators and help- 
ers not already using ATRS systems should 
be provided with formal hands-on training 
in the use of the ATRS system. 

6. The Department of Mines should con- 
duct a series of seminars on current ATRS 
technology and waiver granting proce- 
dures. These seminars should be struc- 
tured to review the current status of 
ATRS technology and, most importantly, 
inform the mining industry of the re- 
quirements and interpretation of the ATRS 
law. 

7. The Department of Mines should 
send a letter of reminder to all under- 
ground coal mine operators regarding the 
March 1984 effective date of the ATRS 
regulations. 

Although nearly all manufacturers have 
either developed or are actively work- 
ing on developing ATRS for their roof 
bolters, and a few are gearing up to 
meet the expected retrofit demand, this 
was not the case with the majority 
of the manufacturers. They seem to be 
waiting for orders from operators before 
manufacturing and stocking retrofit 
kits. We believe that this lack of pre- 
paredness for the anticipated surge in 
demand for ATRS kits could create back- 
log problems as the deadline approaches. 
However, some larger companies that 



own and operate their own rebuild shops 
are already retrofitting all their roof 
bolters with ATRS, and some smaller 
welding shops are also involved in or 



17 



preparing to go into this business. This 
should ease the situation to some 
extent. 



OTHER OBSERVATIONS AND SUGGESTIONS 



COSTS ASSOCIATED WITH ATRS 

All retrofitted ATRS systems require 
that the roof bolter be removed from the 
face for this purpose. Therefore, two 
types of costs are involved with retro- 
fitting of an ATRS: (1) costs occur- 
ring from the loss of production and 
(2) expenses attributable to the purchase 
and installation of the ATRS system. The 
costs resulting from loss of production 
depend on a number of variables; most of 
these are subjective in nature and cannot 
be quantified easily. Although the 
second cost category should be avail- 
able from manufacturers or retrofit 
shops, many medium- to large-sized opera- 
tors typically schedule roof bolter over- 
hauling with retrofitting of ATRS. This 
makes it difficult to accurately estimate 
the cost of retrofitting alone. The cost 
of many ATRS systems for dual-boom bolt- 
ers can be considered irrelevant since 
most of them already have ATRS. The 
costs associated with retrofitting thin- 
to medium-seam roof bolters range from 
about $6,000 to $15,000. 

SOME CONCERNS ON THE ATRS LAW 
AND RELATED MATTERS 

Coal mine operators and safety direc- 
tors expressed the following concerns 
about the effects of the ATRS law: 



1. Does the ATRS law prohibit the use 
of any kind of posts at all in under- 
ground mines at the working place? 

2. Does the ATRS law prohibit the use 
of posts (timber or mechanical) as addi- 
tional temporary support with an ATRS if 
roof conditions so demand? 

3. Does the ATRS law prohibit the 
presence of men beneath unsupported roof 
under all circumstances? 

The answers to these three questions 
are all "no," so the fears of many mine 
operators regarding the ATRS regulations 
are unfounded. 

In general, the overall reception to 
the law has been positive. This under- 
scores the safety features of the law, 
which are recognized as desirable by all 
concerned. Interviews with manufactur- 
ers, mine operators, users, fabricators, 
R&D engineers, etc., showed that most of 
them are fully aware of the West Virginia 
ATRS law. Although some reservations to 
the law were observed as noted above, 
these were primarily due to lack of over- 
all understanding of its intent and ap- 
plicability. Therefore, we reiterate the 
need for a clarification of these con- 
cerns by the West Virginia Department of 
Mines. 



REFERENCES 



1. State of West Virginia. Department 
of Mines Annual Report and Directory of 
Mines, Years 1969 through 1979. 

2. Chislaghi, C. T. , and T. E. Mar- 
shall. Field Test of An Automated Tempo- 
rary Roof Support (ATRS) on a Low-Coal, 



Single Fixed-Head Roof -Bolting Machine 
(Squirmer). BuMines TPR 119, 1982, 
11 pp. 

3. Peng, S. S. Coal Mine Ground Con- 
trol. Wiley, 1978, pp. 31-32. 



18 



FIELD TEST OF AN ATRS SYSTEM ON A LOW-COAL, SINGLE FIXED-HEAD 
ROOF BOLTING MACHINE (SQUIRMER) 

By Edward A. Barrett 1 and Thomas E. Marshall 2 



ABSTRACT 



An economical, remotely operated (auto- 
mated) , temporary roof support (ATRS) has 
been developed by the Bureau of Mines for 
use on a single fixed-head roof bolting 
machine (squirmer) that operates in low 
coal seams (less than 42 in thick) . The 
ATRS eliminates the need for squirmer 
operators and helpers to go under unsup- 
ported roof to set or remove temporary 
support prior to or during the roof 
bolting cycle — a task that annually ac- 
counts for approximately 20 pet of all 



roof fall fatalities. The ATRS can be 
adapted to any squirmer used in the U.S. 
low coal fields. A prototype ATRS was 
field-tested at Imperial Colliery Co.'s 
Mine No. 20 in Eskdale, WV. The Mine No. 
20 amended roof -control plan, which re- 
quires the use of the Bureau's ATRS as 
temporary support during face bolting, 
has been approved by the Mine Safety and 
Health Administration (MSHA) , U.S. De- 
partment of Labor. 



INTRODUCTION 



The Bureau developed an ATRS for 
three reasons: (1) Squirmer operators 
and helpers are exposed to unsupported 
roof on a daily basis, (2) West Virginia 
mine law 3 requires ATRS on squirmers, and 
(3) original equipment manufacturers and 
coal mine operators have not developed 
adequate ATRS for squirmers. 

A statutory provision of the Federal 
Coal Mine Health and Safety Act of 1969 
states that "No person shall proceed be- 
yond the last permanent support unless 
adequate temporary support is provided" 
(30 CFR 75.200). However, since the law 
was written, there have been no practical 
means available that would allow squirmer 
operators and helpers to set temporary 
supports from under permanently supported 
roof. Therefore, this provision was in- 
terpreted to mean "In areas where per- 
manent artificial support is required, 
temporary support should be used until 

1 Mining engineer. 

2 Engineering technician. 
Pittsburgh Research Center, Bureau of 
Mines, Pittsburgh, PA. 

3 West Virginia Administrative Regula- 
tions, chapter 22-4, series 21, March 
1981 . 



such permanent support is installed," and 
"Only those persons engaged in installing 
temporary support should be allowed to 
proceed beyond the last permanent sup- 
port until such temporary supports are 
installed" [30 CFR 75.200-13 (a) (1-2)]. 
Annually, approximately 20 pet of all 
roof fall fatalities involve miners who 
have gone beyond the last permanent sup- 
port to set or remove temporary roof sup- 
port prior to or during the roof bolting 
cycle. 

Low coal mine operators in West Vir- 
ginia need ATRS because the State mine 
law requires that roof bolting machines 
used in working places be equipped with 
ATRS, regardless of coal seam height. 
New machines must be equipped by 1982, 
and all machines by 1984. 

Over 3,500 squirmers are in use today 
in southern West Virginia, eastern Ken- 
tucky, and southwestern Virginia, and ap- 
proximately 60 pet of these have no ATRS, 
cab, or canopy. Because of space limita- 
tions in low coal, not many ATRS have 
been commercially developed for squirm- 
ers, although many different ATRS systems 
have been commercially developed for roof 
bolting machines used in high coal. Most 



ATRS designed for squirmers reduce work- 
space and operator visibility, creating a 
situation that reduces or compromises the 
existing safety level, with a greater 
safety hazard to squirmer operators and 
helpers working inby the last row of per- 
manent support. 



19 



All design work and prototype fabrica- 
tion of the Bureau ATRS was done by the 
Roof Support Group at the Pittsburgh Re- 
search Center. All fieldwork was done in 
the No. 2 gas seam (36 to 42 in thick) at 
Mine No. 20 of the Imperial Colliery Co. 
in Eskdale, WV. 



ACKNOWLEDGMENTS 



The Bureau acknowledges the coopera- 
tion it received from the Imperial Col- 
liery Co. , especially the personnel of 
Mine No. 20, who participated enthusias- 
tically in the modifications and tests. 
In addition, the Bureau acknowledges the 
cooperation of the Mine Safety and Health 



Administration (MSHA) , U.S. Department 
of Labor; in particular, personnel of 
the Bruceton Safety Technology Center 
and the Mount Hope Subdistrict. Without 
their technical suggestions and assist- 
ance, this project could not have been 
completed. 



DESCRIPTION OF ATRS 



The Bureau of Mines' ATRS is a 10-ft- 
long, steel, wide-flange beam supported 
by two double-acting, telescoping hydrau- 
lic cylinders (fig. 1). A steel sleeve, 
mounted on the bottom center of the beam, 
is designed to fit over the top of the 
squirmer drill head (fig. 2). The ATRS 
is carried from place to place and from 
row to row on the squirmer drill head 
(fig. 3). During bolting it is connected 
to the squirmer only by two hydraulic 
lines (fig. 4). Because the ATRS weighs 
only about 400 lb, the squirmer drill 
head and boom do not have to be rebuilt 
to carry it. Total cost of the beam and 
cylinders is approximately $1,800. In- 
house fabrication of the ATRS took 8 
worker-hours. The Bureau piped the ATRS 
hydraulic circuit at a cost of $150 and 
32 worker-hours. 



The Bureau's ATRS design meets MSHA's 
general design requirements and West Vir- 
ginia's design and operating requirements 
for such support. Both hydraulic cyl- 
inders supporting the ATRS have check 
valves to prevent sudden collapse of the 
ATRS in the event of a ruptured hydraulic 
line or broken hydraulic fitting. In ad- 
dition, the ATRS hydraulic circuit con- 
tains an accumulator, charged by squirmer 
line hydraulic pressure, which keeps the 
ATRS firmly set against the mine roof 
even if the roof rock is pulled up during 
the bolting cycle. The ATRS can elasti- 
cally support the minimum required dead- 
weight load of 33,750 lb. 4 Figures 5 
through 8 include all design drawings and 
the hydraulic schematic. 



SQUIRMER STREAMLINING 



West Virginia State mine law requires 
the streamlining of any roof bolting 
machine before it can be retrofitted 
with ATRS. Imperial Colliery personnel 
streamlined a 15-yr-old squirmer for the 
field test. The ATRS controls were lo- 
cated 5 ft back from the drill head so 
that they can be operated only from be- 
neath permanently supported roof (fig. 
9). Full tram controls are located with 
the ATRS controls, and the full tram 



speed was left at 150 ft/min. Inch-tram 
controls were located at the drill sta- 
tion, and inch tram speed was reduced to 
65 ft/min. No ATRS controls were located 
at the drill station. Other streamlin- 
ing work included removal of the bolt 
tray and tram deck, installation of low 
volume-high torque tram motors, and 

^Capacity certified by a professional 
engineer. 



20 




FIGURE 1. - Bureau of Mines ATRS. 




"IGURE 2. - ATRS mounted on drill head for transport from place to place. 



21 




FIGURE 3. - ATRS carried from place to place. 




FIGURE 4. - ATRS location during bolting. 



22 



6- by 6- by 0.3-in web or 
heavier steel, IO-ft long 



.0, 





Steel sleeve 

Stiffeners, 7each side 

Inside cylinder stops 

I- by I- in bar steel 

4 in long welded to 

connection plate 



FIGURE 5. - General assembly of ATRS. 



moving the squirmer front wheels 8 in 
forward to provide space for the ATRS and 
full tram controls. Total cost of this 



work was $5,500 and it 
worker-hours to complete. 



required 96 



FIELD TEST AND RESULTS 



With MSHA and West Virginia approval, 
Imperial Colliery placed the ATRS in the 
production cycle at Mine No. 20 for 5 
months. Bolting was on 4-ft centers in 
20-ft-wide entries and crosscuts. For 
the Bureau's ATRS, the bolting cycle was 
the following: 

Step 1 . - The squirmer operator, at the 
full tram controls (fig. 9), trams into 



the center of an entry and stops when the 
ATRS is under the last row of permanent 
support. 

Step 2 . - The operator lowers the drill 
head and ATRS to the mine floor, using 
the boom control located beside the full 
tram and ATRS controls; moves from the 
full tram position to the beam (ATRS) ; 
and unhooks the hydraulic cylinder leg on 



23 




L't 




Hydraulic jack 



FIGURE 6. = Detail of ATRS connection with- 
out cylinder stop. 

the operator side that is chained to the 
beam, while the helper does the same to 
the leg on the right side (fig. 10). 

Step 3 . - The operator raises the drill 
head and ATRS, using the boom control at 
the drill station, just high enough to 
let the legs hang down perpendicular to 
the mine floor; locks the legs perpendic- 
ular to the mine floor; moves back to the 
full tram and ATRS controls; and trams 
the squirmer inby. 

Step 4 . - The operator stops when under 
the last row of permanent support. The 
ATRS is now 5 ft inby the last row of 
permanent support and 5 ft from each rib. 

Step 5 . - The operator places the ATRS 
against the roof, using the boom control 
located beside the full tram and ATRS 
controls, and then extends the legs to 
the mine floor, using the ATRS control, 
until the beam is firmly set against the 
roof and the legs are firmly set against 
the mine floor. 



6- by 6- by 0.3-in web or 
heavier steel, 10 ft long 





-Stiffener (7) 



i-inweld, bottom flange 
and web 



— V i 

^4- in weld, all around 



FIGURE 7. - End view of ATRS and connection 
without cylinder stop. 

Step 6 . - The operator lowers the drill 
head away from the beam, using the boom 
control located beside the full tram and 
ATRS controls. 

Step 7 . - At this point, the operator 
moves to the drill station, pushes in the 
diversion valve, which diverts all hy- 
draulic fluid from the full tram and ATRS 
circuits to the inch tram and drill cir- 
cuits, and "inches" the squirmer to the 
left rib to begin bolting. During bolt- 
ing the squirmer is connected to the ATRS 
only by two hydraulic lines (fig. 4). 

Step 8 . - After a row of permanent sup- 
port is installed, the operator raises 
the drill head into the beam, using the 
boom control at the drill station; pulls 
out the diversion valve, which diverts 
all the hydraulic fluid back to the full 
tram and ATRS circuits from the inch tram 
and drill circuits; moves to the full 
tram and ATRS controls; and retracts the 
legs, using the ATRS control. 



24 



Boom 
jack 



Drill motor 
V 




Drill circuit 

•Mvj~f| Relief valve 



FIGURE 8. - Hydraulic schematic of ATRS for streamlining. 



Step 9 . - The operator lowers the drill 
head and ATRS, using the boom control lo- 
cated beside the full tram and ATRS con- 
trols, just enough to tram the squirmer 
4 ft inby. 

Step 10 . - When under the row of perma- 
nent roof supoort that has just been in- 
stalled, the operator stops and repeats 
steps 5 through 9. This cycle is re- 
peated until the last bolt is in place. 

Step 11 . - Then the operator raises the 
drill head into the beam, using the boom 
control at the drill station; unlocks 
the legs; pulls out the diversion valve; 
moves to the ATRS controls; retracts the 
legs; moves back to the drill station; 



lowers the drill head and ATRS to the 
mine floor, using the boom control at 
the drill station; chains the leg on 
the operator side to the beam, while the 
helper does the same to the leg on the 
right side; moves back to the full 
tram and ATRS controls; and trams to the 
next place, where steps 1 through 11 are 
repeated. 

No operating or maintenance problems 
were encountered during the 5 months of 
testing. With the addition of the ATRS, 
the squirmer could still turn 180° within 
the 20-ft-wide entries and crosscuts, and 
could tram through check curtains and 
line brattice without pulling them down. 
Comparative time studies of the same 



25 




FIGURE 9. - Control bank locations. 



bolting crew showed that it took an aver- 
age of 5 min less to bolt a place with 
the ATRS than with mechanical jacks. The 
bolting crew preferred the ATRS. After 
testing, an amended roof control plan 
requiring the use of the Bureau's ATRS 



during face bolting at Mine No. 20 was 
submitted by the Imperial Colliery Co. 
and approved by MSHA (District 4, Mount 
Hope Subdistrict, Montgomery Field 
Office). 



CONCLUSIONS 



The Bureau 1 s ATRS eliminates the need 
for squirmer operators and helpers to go 
under unsupported roof to set or remove 
temporary support prior to or during the 
roof bolting cycle. The squirmer opera- 
tor will always be under permanently sup- 
ported roof while setting or removing the 
ATRS and will not be able to bolt inby 
the ATRS because of its size and position 
in the entry. In addition, this inexpen- 
sive and lightweight ATRS does not reduce 
the squirmer operator's workspace. 



The ATRS has the potential to be imme- 
diately used in U.S. coal mines. Al- 
though the Bureau's ATRS was field-tested 
with only one squirmer, it can be adapted 
to the drill head of any squirmer operat- 
ing in low coal and it can be fabricated 
in any mine shop. The ATRS can be retro- 
fitted to the squirmer during mainte- 
nance shifts if a streamlined squirmer is 
available. 



26 




FIGURE 10. - ATRS hydraulic cylinder legs unhooked. 



Bolting does not stop if problems oc- 
cur with the Bureau's ATRS, since it can 
be removed from the area and bolting can 
continue with mechanical jacks serving 
as temporary supports. (If problems 
arise or maintenance must be performed 
on any other ATRS, the squirmer must be 
taken out of production.) In addition, 
this ATRS does not have to be reset for 
each bolt hole as do the ring-type and 



ironing-board-type ATRS. It is reset on- 
ly after a complete row of bolts is in- 
stalled. The Bureau's ATRS provides a 
support envelope for the squirmer opera- 
tor and does not obstruct the installa- 
tion of bolts 2 ft from either rib. It 
has the potential to drastically reduce 
roof fall fatalities and injuries and 
lead to increased productivity, if used 
as outlined in this document. 



27 



DEVELOPMENT OF AN ATRS SYSTEM FOR FAIRCHILD INC. ROOF DRILLS 

By George Cobb 1 



FAIRCHILD BOLTING MACHINES 



Fairchild Inc.'s J-4 and J-6 roof bolt- 
ers (fig. 1) have been in existence for 
over 20 yr. When introduced to the in- 
dustry they were immediately accepted 
as the standard for bolting machines 
with continuous mining in low seams. The 
bolters were among the first to have a 
fully enclosed gear-driven tram system, 
which greatly decreased the interference 



of mud or other foreign materials while 
tramming. The Research and Development 
Division of Fairchild, located in Beck- 
ley, WV, has upgraded the bolter through 
the years, such as increasing the hydrau- 
lic capacity and installing a dual lift 
on the bolter head. Now the Research and 
Development Division is introducing an 
ATRS system for the bolters. 



ATRS WITH AN EXTENDED HEAD BOLTER 



At first the Research and Development 
engineers designed an ATRS system com- 
patible with Fairchild' s original bolter 

'Director of marketing, Fairchild Inc., 
Beckley, WV. 



designs. A prototype was developed, 
tested underground, and brought back into 
the laboratory for refinement. Mine op- 
erators, the West Virginia Department of 
Mines, West Virginia Tech University, and 
MSHA provided valuable assistance during 




FIGURE 1. o Standard Fairchild roof bolter without ATRS. 



28 



this process. The ATRS system is now be- 
ing fitted to the newest version of the 



Fairchild bolter, whose extended head is 
capable of reaching 46 in in height. 



OPERATION OF THE ATRS 



The ATRS is mounted on a stand and car- 
ried by a lift arm weldment on the drill 
head of the bolter. First, the operator 
positions the ATRS stand just inby the 
area to be bolted, lowers it to the bot- 
tom by lowering the drill head, and 
raises the ATRS jacks against the roof 
(fig. 2). Each jack is capable of sup- 
porting the roof load required by the 
West Virginia Department of Mines (11,250 
lb) without adversely affecting the frag- 
ile roof strata. The ATRS must pressur- 
ize against the roof before the drilling 
and bolting controls become operational. 

The operator then moves to the drilling 
and bolting controls, backs the machine 
away from the ATRS (figs. 3-4), and folds 



back the lift arm weldment, thus giving 
free access to the drill head. If the 
ATRS has been efficiently positioned in 
the entry, two bolts can be installed (5- 
ft maximum spacing) without repositioning 
the stand. To move the stand, the opera- 
tor folds out the lift arm weldment, po- 
sitions it under the stand, and lowers 
the ATRS jacks to the desired tramming 
height. He then raises the drill head to 
pick up the stand and maneuvers the bolt- 
er until the ATRS is repositioned (fig. 
5) . He repeats this sequence until the 
entire place is bolted according to the 
approved mine bolting plan. A cab and 
canopy at the rear of the bolter protect 
the operator as he trams from place to 
place (fig. 6). 




FIGURE 2. - ATRS jacks extended. 



29 




FIGURE 3. - Rear view of bolter backing away from ATRS stand. 




FIGURE 4. » Front view of bolter backing away from ATRS stand. Note lift arm weldment. 



30 




FIGURE 5. - Lift arm weldment repositioned beneath ATRS stand. 




FIGURE 6. = Boom raised to carry ATRS. Note tram compartment at rear. 



STATUS OF THE PROGRAM 



31 



A second underground trial is scheduled 
during May 1983. This should allow us to 
finish the research and begin full devel- 
opment of the new ATRS system. Although 
West Virginia is the first State to re- 
quire ATRS systems, we believe other 
States will eventually require them. 



Therefore, the Fairchild ATRS system is 
being designed to achieve compliance with 
regulations while providing the maximum 
amount of safety, flexibility, and pro- 
duction. We believe we will be able to 
offer an ATRS retrofit kit to all West 
Virginia customers by March 1984. 



32 



RETROFIT ATRS SYSTEMS FOR ROOF BOLTERS 
By Gary 0. Bledsoe 1 



INTRODUCTION 



G. 0. Bledsoe, Inc., is a small engi- 
neering firm providing services to indus- 
try, commercial development, contractors, 
mining, and the general public. We pro- 
vide professional engineering services on 
canopies and ATRS systems to various man- 
ufacturers and are most heavily involved 
with A&M Welding and Manufacturing Co. , 
Inc., Mullens, WV, in research and devel- 
opment of retrofit packages for ATRS 
systems. 

G. 0. Bledsoe, Inc. , is in a rather 
unique position because we do not repre- 
sent a manufacturer and are primarily 



concerned with the retrofit industry in- 
stead of new equipment. For this reason 
we can look at a variety of designs with- 
out having to sell a particular product 
line. In the development of ATRS sys- 
tems, we have tried to standardize as 
much as possible; however, we found this 
to be very difficult because almost every 
retrofit is a custom design package for 
each manufacturer's equipment and each 
variation of each model. This paper dis- 
cusses the advantages and disadvantages 
of all four types of retrofit ATRS sys- 
tems available today. 



CHARACTERISTICS OF RETROFIT ATRS SYSTEMS 



A good retrofit ATRS system should 
be (1) rugged enough to withstand roof 
loads and lateral impacts, (2) as light 
as possible to improve maneuverabil- 
ity, (3) versatile enough to meet a vari- 
ety of roof conditions, and (4) easy 
to operate and maintain. Also, to sa- 
tisfy ATRS regulations, the retrofit sys- 
tem must be designed such that the 
machine operator is always under perma- 
nently supported roof while installing 
the ATRS, and the hydraulic ATRS sup- 
port jack(s) must contain a pilot check 
valve(s) to prevent accidental collapse. 
Unfortunately, many existing roof bolt- 
ers were not designed to accommodate 
ATRS structures. Furthermore, some ma- 
chines with ATRS systems were not de- 
signed to meet the requirements of the 
ATRS regulations now in place. There- 
fore, many existing machines will have 



to be modified in some 
compliance. 



manner to achieve 



Installing a retrofit ATRS system is 
not a simple matter of attaching a roof 
support structure to the bolter; the ma- 
chine itself must be modified substan- 
tially to obtain a good, "legal" ATRS 
system. Possible machine modifications 
include (1) adding inch-tram and/or ATRS 
positioning controls, (2) relocating ex- 
isting controls, (3) adding or modifying 
the tramming deck and canopy, (4) revis- 
ing structural framework to support the 
ATRS structure, (5) adding newer, more 
powerful tram motors, and (6) general 
overhaul of the machine to obtain opti- 
mum performance. The cost of performing 
these modifications is often equal to or 
greater than the cost of the ATRS system 
itself. 



TYPES OF RETROFIT ATRS SYSTEMS 



RING-TYPE 



Figures 1-3 show a typical ring-type 
ATRS system on a single-head roof bolter. 

1 President, G. O. Bledsoe, Inc., Beck- 
ley, WV. 



Figure 1 shows the system deployed in a 
mine entry, and figures 2 and 3 show the 
system when it was first installed on 
the bolter in a rebuild shop. The ring 
in these figures is 36 in in diameter 
(smaller or larger rings can be used) and 
is centered around the point where the 



33 




FIGURE 1. - Ring-type retrofit ATRS deployed in mine entry. 




FIGURE 2. » Ring-type ATRS being installed in rebuild shop - front view. 



34 




FIGURE 3. = Ring-type ATRS in rebuild shop = rear view. 



35 



drill steel enters the mine roof. The 
ring is mounted on a pair of steel arms 
and is raised to the roof by a hydraulic 
jack(s). It must be retracted and reset 
prior to each roof bolt installation be- 
cause the ring only supports the mine 
roof in the immediate vicinity of each 
roof bolt hole. 

Since the ring-type ATRS system is rel- 
atively small and maneuverable compared 
to other ATRS systems, many mine opera- 
tors feel it is the best system avail- 
able. However, one disadvantage of the 
ring design is that it usually contacts 
the roof at only two points; thus, high 
twisting stresses can occur in the sup- 
port arms when the ring tries to con- 
form to the irregular contour of the mine 
roof. The designs of some ring and sup- 
port arm structures result in roof con- 
tact at only one point, further increas- 
ing the twisting stresses. 

Installation of a retrofit ring-type 
ATRS system on a high-coal machine is 
rather simple — the support arms, pivots, 
and jacks can be welded directly on top 
of the machine frame. In low coal, how- 
ever, the ring must often be dropped 
below the machine frame height, so the 
support arms and pivots must also be 
recessed below the frame. In most cases, 
this modification is quite difficult 
and expensive because the machine must 
be stripped down to its main frame to 
provide the necessary clearances. Ring- 
type retrofit ATRS systems appear to be 
applicable to bolters in seams as low as 
32 in. 

H-FRAME 

Figures 4 and 5 show the H-frame retro- 
fit ATRS system designed by G. 0. Bled- 
soe, Inc. , and fabricated by A&M Welding 
and Manufacturing Co. for single-head 
roof bolters. Although the H-frame, like 
the ring-type ATRS, was designed to sup- 
port only the roof area in the vicinity 
of one bolt, we prefer it to the ring 
type because (1) the H-frame will usual- 
ly contact the mine roof at three or four 



points, versus one or two for the ring 
type and (2) the cantilevered design of 
the H-frame allows it to support more 
roof area than the ring type (an 8- by 
8-ft versus a 5- by 5-ft area). Figure 
6 shows an alternative version of the 
H-frame design; in this case, the middle 
portion of the "H" in figures 4 and 5 is 
eliminated, and two separate hydraulic 
jacks are used to raise the remaining two 
portions of the roof support structure. 
This design provides more flexibility in 
uneven roof conditions than either the 
H-frame or the ring-type ATRS. 

The H-frame and modified H-frame retro- 
fit ATRS systems share two of the disad- 
vantages of ring-type retrofit systems. 
First, the retrofit process is usually 
rather difficult and expensive, involving 
changes to the tramming station, bolter 
frame, and machine hydraulic system. 
Second, the H-frame has limited applica- 
tion to very low coal. Note that the 
H-frame structures in figures 4, 5, and 6 
are made of 4-in-deep structural tubing 
that would increase the tramming height 
of the bolters unless special modifica- 
tions were made. For this reason, G. 0. 
Bledsoe and A&M Welding have developed a 
low-profile H-frame made of 1-in-thick 
steel plate, reinforced with stiffeners. 
The lowest tramming height attainable 
with the low-profile H-frame is approxi- 
mately 32 in. 

BAR-TYPE 

Bar-type ATRS systems are different 
from ring-type or H-frame designs because 
the bar is usually designed to support 
the roof area normally supported by one 
complete row of roof bolts (sometimes two 
rows) rather than just one bolt. Because 
of this , many operators believe the bar- 
type system is inherently safer than any 
single-bolt system. In addition, the 
bar-type system can improve productivity 
because a complete row of bolts can be 
installed with each ATRS setup. Almost 
all newly manufactured dual-head roof 
bolters contain some form of bar-type 
ATRS system. 



36 




FIGURE 4. - H=frame retrofit ATRS on single=head bolter. Note streamlined control station. 




FIGURE 5. - H-frame retrofit ATRS deployed in mine entry. 



37 




FIGURE 6. - Alternative H-frame ATRS - center portion removed. 



In terms of retrofit, however, the bar- 
type ATRS system has some distinct dis- 
advantages compared to ring-type and 
H-frame systems, especially with the 
small single-head bolters that are most 
likely to require retrofitting. Because 
the bar is usually heavier, bulkier, and 
cantilevered farther forward than ei- 
ther the ring or the H-frame, a bolter 
equipped with a bar-type retrofit system 
may be difficult to tram and maneuver 
around corners. The bar may also be dif- 
ficult to set up in working places where 
the face and ribs do not form rectangular 
corners; this often occurs in conven- 
tional sections where the coal is blasted 
rather than cut from the face. The extra 
time required for these maneuvering tasks 
may totally negate the productivity ad- 
vantages gained by the ability to install 



more than one bolt per ATRS set up. That 
is, if a ring or H-frame ATRS system is 
simple and responds rapidly, it could re- 
sult in a faster overall bolting cycle 
time than a bar-type system. Further- 
more, the heavier, bulkier bar often re- 
quires a far more difficult (and some- 
times impossible) retrofit task than the 
other two methods. Thus far, only one 
retrofit bar-type system, designed by the 
Bureau of Mines, is now available to coal 
mine operators. 

JACK-TYPE 

The jack-type ATRS system is as simple 
as implied by its name — a single hydrau- 
lic jack (or a set of jacks) is thrust 
directly against the roof to provide sup- 
port in the immediate vicinity of the 



38 



jack itself. Although its coverage is 
very limited compared to that of the 
other three types of ATRS systems de- 
scribed above, it is much simpler and can 
be retrofitted more easily to the bolting 
machines . 

The primary application of the jack- 
type ATRS system thus far has been as a 
supplementary support, used in conjunc- 
tion with a bar-type system. However, 
the jack-type system is probably the most 
appropriate system for very low coal 
seams because it lacks the ring, H-frame, 



or bar-type structures that require 
greater vertical clearance. The lack of 
a large load-bearing support structure 
on top of the jacks also makes the jack- 
type system less susceptible to machine- 
induced ATRS failure. That is, the up- 
ward thrust of the jacks on the ring, 
H-frame, or bar can sometimes induce 
stresses that exceed the rock load for 
which the structures were designed. Spe- 
cial care must be taken when designing 
these three systems to avoid excess up- 
ward thrust loads. 



NEED FOR RETROFIT ATRS SYSTEMS 



Considering that most of the single- 
head roof bolters now being used in 
southern West Virginia do not contain 
ATRS systems, a great deal of retrofit- 
ting work will need to be done in order 
to comply with the March 1984 deadline 
specified in the West Virginia ATRS regu- 
lation. G. 0. Bledsoe, Inc, , and A&M 
Welding and Manufacturing Co. are in a 
position to help meet these needs because 
we have developed and installed retro- 
fit ATRS designs for Fletcher, Lee- 
Norse, Acme, and FMC (Galis) roof bolt- 
ers. About 30 pet of all retrofit ATRS 
systems now being used in the Appalachian 
coalfields have been designed and in- 
stalled by our companies. 

Mine operators must remember that sim- 
ple retrofit kits for their machines are 
not sufficient; the systems must be in- 
stalled by persons with intimate knowl- 
edge of both the ATRS requirements and 



the design of the roof bolter itself. In 
each case, the mine operator must decide 
whether to retrofit the existing bolt- 
er or replace it with a new machine de- 
signed specifically to accommodate an 
ATRS system. 

Although retrofits are not cheap, they 
are less expensive than buying a new 
machine; on the other hand, a newly de- 
signed machine will often contain a neat- 
er, more advanced, and more maneuverable 
ATRS package. If capital is available, 
the new machine option is probably the 
best one to choose. Most small mine op- 
erators, however, will not be able to 
afford new machines; therefore, they 
should consider the advantages and disad- 
vantages of each type of retrofit system 
very closely. It is hoped that this pa- 
per will help them make their decisions 
regarding retrofit ATRS systems. 



THE SCHROEDER FRONTRUNNER ROOF BOLTER WITH ATRS SYSTEM 
By Gus Schroeder 1 



39 



The Frontrunner is a twin-head bolter 
designed to operate in coal seams from 55 
to 84 in high. To allow the machine op- 
erators to work in the safest possible 
conditions, both operators are able to 
perform all functions associated with 
roof bolting, including tramming, from a 
single, well-protected position on the 
machine. The Frontrunner' s design places 
the operators in two compartments located 
at the front of the machine (figs. 1-2). 
Each compartment is covered by a protec- 
tive canopy that can be adjusted hydrau- 
lically to afford the maximum height 
within the compartment at all times. 

During bolting operations, the primary 
operator protection is provided by an 



' Schroeder 
Rocks, PA. 



Brothers Corp., McKees 



ATRS located directly in front of the op- 
erators' compartments. Drilling is done 
with a mast-type assembly which provides 
for hands-off drilling by incorporating 
both a deep drill chuck and a practical 
drill steel centralizer. The drill masts 
are located at the front of each opera- 
tor's compartment (fig. 3) and can be 
shifted hydraulically across the full 
length of the compartment. The compart- 
ments themselves can be expanded lateral- 
ly to a fully extended width of 185 in. 
Figure 4 shows the compartments in their 
fully retracted positions, and figure 5 
shows the left compartment extended to- 
ward the rib. Because both the compart- 
ments and the drill masts can be adjusted 
laterally, a complete row of bolts can be 
installed without having to reposition 
the entire machine. 




FIGURE 1. - Overall view of FRONTRUNNER roof bolter - ATRS lowered. 



40 




FIGURE 2. - Overall view of FRONTRUNNER roof bolter - ATRS raised. 




FIGURE 3. - Side view of sliding drill mast. 



41 




FIGURE 4. - Rear view - compartments retracted. 




FIGURE 5. - Left compartment extended toward rib. Note tool tray. 



42 



The following sequence occurs during 
the normal installation of one set of 
bolts (four bolts per row). The operator 
trams the Frontrunner into the center of 
the working place and spots the drill 
heads for the first row of bolt holes. 
He then raises the ATRS to support the 
roof and lowers both compartments to the 
floor. The drill masts are then posi- 
tioned inward for proper hole location, 
and the center two bolts are installed. 
The compartments are then repositioned 
outward toward the mine ribs, the drill 
masts are repositioned, and the outer two 
bolts are installed. 

After the first complete row of bolts 
is installed, the operator slightly col- 
lapses the ATRS, trams forward to spot 
the drill heads for the next row, and re- 
sets the ATRS. During this brief period 
of repositioning, protection is provided 
for the operators by the canopies over 
each compartment. Because the operators 



always face one another within their com- 
partments (fig. 6), each has full view of 
the other during both drilling and tram- 
ming. From their seated positions the 
operators can easily reach the drill 
heads in front of them and the tool trays 
behind them (fig. 5). Each tool tray 
is connected to the back of the opera- 
tor's compartment and follows the com- 
partment as it expands. Access to drill 
steels, roof bolts, and other necessary 
supplies remains convenient regardless 
of where the compartments are posi- 
tioned. The design of the Frontrunner' s 
operating compartments, therefore, pro- 
vides a safe, efficient, and comfortable 
working environment. 

Safety has also been a key considera- 
tion in the design of the Frontrunner' s 
operating controls. Control levers 
(figs. 7-8) have been grouped together 
in logical relationship to the sequence 
of their function in the bolting cycle. 




FIGURE 6. - Bolter operators maintain visual communication during bolting cycle. 



43 




FIGURE 7. • Control layout within operator compartment. 






FIGURE 8. - Closeup of ATRS controls. 



44 



Maximum speeds of the various functions 
have been set at levels that allow 
the operator to maintain control of the 
machine. The left side operating com- 
partment contains the primary control 
system with individual controls for 
(1) tramming, (2) raising and lowering 
the ATRS, (3) moving the left compart- 
ment, (4) raising and lowering the left 
side canopy, and (5) operating the left 
side drill head and mast. The right side 
operating compartment contains controls 
only for the right side drill head and 
mast, movement of the right compartment, 
and height adjustment of the right side 
canopy. Panic bars that stop all opera- 
tions are conveniently located in both 
compartments . 

To ensure that the Front runner can be 
trammed easily, the steering system is 
similar to that found in an automobile. 
Tramming speed is governed by a foot- 
operated accelerator which controls speed 
from to 88 ft/min. Steering is accom- 
plished with a steering wheel rather than 
the lever arrangement found on most min- 
ing machines. If the wheel is turned 
right, the machine turns right. If the 
wheel is turned left, the machine turns 
left. The turning radius of the machine 
becomes tighter as the wheel is turned. 
This automotive-type steering system al- 
lows even inexperienced machine operators 
to tram the machine safely. 

Location of the operator at the front 
end of the Frontrunner affords maximum 
visibility while tramming forward. When 
tramming in reverse, he or she can obtain 
an undisturbed line of sight down the 
side of the machine by moving the left 
side compartment slightly out from the 
main frame. When the machine is in the 
tram mode, each operator retains the 
ability to raise and lower the height of 
his or her compartment and canopy to com- 
pensate for variations in seam height. 
When only one person is on the machine 
during tramming, controls for the right 
side canopy and compartment can be 
switched over to the left side compart- 
ment. The Frontrunner* s design allows 



both operators to ride inside the protec- 
tive compartments while the machine is 
moving from one working place to another. 
This feature reduces the possibility that 
the operators can become pinned between 
the machine and the mine rib. 

Both the tram and ATRS functions on the 
Frontrunner can also be controlled re- 
motely (fig. 9). A control box connected 
to the rear of the machine by an electri- 
cal cable allows machine positioning and 
setting of the ATRS to be done without 
either operator being physically located 
on the machine. 

As stated earlier, the ATRS provides 
the primary protection against roof falls 
while the Frontrunner is in the drilling 
mode. When fully collapsed (fig. 10) , 
the scissors-type ATRS is only 38 in 
high, which is less than the height of 
the machine frame. When fully expanded 
(fig. 11), the ATRS reaches a height of 
slightly over 9 ft. Use of the scissors- 
type ATRS design allows for about 6 ft of 
height variation in the ATRS without us- 
ing telescoping hydraulic cylinders. 

The ATRS is expanded by means of three 
double-acting hydraulic cylinders. The 
cross beam is raised and lowered by two 
cylinders which drive the scissors link- 
age arms. Hydraulic oil is furnished 
from a single control valve and then di- 
vided equally to each cylinder. A third 
cylinder, located in the main ATRS sup- 
port housing, vertically lowers 1 ft from 
the housing to maintain ground contact 
(fig. 12). All three of these cylinders 
incorporate the required built-in pilot 
check valves . 

The main support housing of the ATRS is 
mounted in a pivoted fashion on the boom, 
allowing the entire ATRS to be tilted by 
means of another hydraulic cylinder (fig. 
13). This allows the ATRS to be adjusted 
to conform to the contour of each working 
face so that the last row of bolts can be 
installed as close to the face as possi- 
ble. The ATRS boom itself can also be 
raised and lowered hydraulically. In 



45 




FIGURE 9. - Optional remote control tramming from rear of bolter. 




FIGURE 10. - ATRS collapsed - 38=in overall height. 



46 




FIGURE 11. - ATRS fully extended to 9-ft height. 




i^pvpp p.. . 

::M'?P&PPr-. 



FIGURE 12. - ATRS stab foot maintains ground contact. 



47 




FIGURE 13. - ATRS beam tilted toward face. 



total, four controls are used to operate 
the ATRS: boom raise and lower; ATRS 
tilt; ATRS foot; and ATRS expand and con- 
tract. The controls are grouped together 
in the left side operator's compartment. 

Small rocker beams are located at each 
end of the main cross beam of the ATRS, 
and the cross beam itself is pivoted at 
the center. These features allow the 
ATRS to conform to the coal seam roof 
line. During periods when the ATRS is 
not set, the cross beam is maintained in 
a horizontal position by two large drop 
coil springs which run from the cross 
beam to the ATRS scissors arms. To pre- 
vent any overstressing of the ATRS assem- 
bly that might occur as a result of acci- 
dentally bumping the mine rib or roof 
while tramming, all the pivot points have 



been designed to have some degree of 
freedom of movement. 

In summary, the major safety feature of 
the Frontrunner roof bolter is that its 
design allows both machine operators to 
perform all roof bolting functions, in- 
cluding tramming, from a single location 
on the machine. The use of two canopy- 
equipped operator compartments and an 
ATRS system provides protection for both 
operators at all times. Although our 
ATRS system was designed for use on the 
Frontrunner bolter, Schroeder Brothers 
may explore the possibility of adapting 
it to other dual-head roof bolters. Our 
ATRS system meets all applicable ATRS 
requirements outlined in the West Vir- 
ginia Mine Regulations. 



48 



REMOTELY ACTUATED TEMPORARY SUPPORT (RATS) 
FOR FMC UNDERGROUND MINING EQUIPMENT 



By Martin D. Wotring 



The 1969 Coal Mine Health and Safety 
Act required the installation of canopies 
on face equipment. Considerable opposi- 
tion to the use of the canopies in low 
seams caused MSHA to waive the original 
canopy requirements in seams under 42 in. 
This left a large percentage of coal 
miners without any form of roof fall pro- 
tection. An analysis of fatalities due 
to roof falls for 1972-75 revealed that 
roof bolters and their helpers suffer the 
largest percentage of fatalities (17.5 
pet) , and that setting temporary posts or 
jacks is the activity with the largest 
percentage of fatalities (18.5 pet). Of 
course, since the roof bolter and helper 
usually set the temporary support during 
the normal course of the bolting opera- 
tion, these percentages indicated the 
need for some method to prevent a worker 
from going beyond permanent roof support 
to set these posts or jacks. 

FMC first installed remotely actuated 
supports (RATS) on dual-boom roof bolters 
in 1974. This "ironing board" style RATS 
was used in place of the canopies over 
the drilling stations (fig. 1). At the 
1976 American Mining Congress convention 
in Detroit, FMC displayed its first roof 
drill with a ring-type roof support (fig. 
2) This was a single-boom drill that also 
incorporated a drill steel guide within 
the support and a canopy over the opera- 
tor's deck. At the same time, ring-type 
and ironing-board-type RATS were being 
tried on existing single-boom drills as 
retrofit kits (figs. 3-4). Dual-boom 
roof bolters with ring-type RATS and 
drilling canopies (fig. 5) were also 
developed. 

1 Lead engineer, roof bolters, FMC 
Corp., Mining Equipment Division, Fair- 
mont, WV. 



Dual-boom roof bolters with beam-type 
RATS (fig. 6) became available in 1977. 
This type of RATS features four roof con- 
tact pads which are less than 5 ft apart. 
The pads swivel, as does a rocker arm to 
which the pads are connected. This per- 
mits the RATS to conform to uneven tops. 
The overall width of the beam-type 
RATS can be 8 to 10 ft. Figure 7 shows 
a beam-type RATS on a dual-boom drill de- 
signed for angle bolting. 

FMC introduced a single-boom roof drill 
with a beam RATS at the 1980 American 
Mining Congress convention in Chicago 
(fig. 8). This machine has essentially 
the same type beam support as a dual-boom 
bolter, but the drill unit pivots hori- 
zontally to allow the installation of a 
complete row of four bolts on 4-ft cen- 
ters. It has the capability to extend to 
allow the row of bolts to be installed 
in a straight line across the entry. 

A single-mast drill was exhibited at 
the 1982 American Mining Congress conven- 
tion in Las Vegas. This machine has 
space in the operator's deck for both the 
driller and helper, and both are covered 
by a canopy. The RATS is attached to the 
deck just ahead of the mast. The deck 
can be lowered to the floor and the RATS 
engaged against the roof for support, 
thus protecting both workers. 

FMC has also been involved with two Bu- 
reau of Mines roof support research pro- 
grams. One was to design, build, and 
test a lightweight, manually installed 
support jack (fig. 9). This jack is 
self-contained, is hydraulically actuated 
with a lanyard release, supports 22 tons, 
and weighs only 54 lb. 



49 




FIGURE 1. - Dual-boom roof bolter with ironing°boarcUtype RATS. 




FIGURE 2. - Single=boom roof bolter with ring-type RATS, operator's deck, and canopy. 



50 




FIGURE 3. - Single-boom roof bolter with retrofit ring-type RATS. 





rffflft 



FIGURE 4. - Single=boom roof bolter with ironing=board=type RATS. 



51 




FIGURE 5. - Dual-boom roof bolter with ring-type RATS. 




FIGURE 6. - Dual-boom roof bolter with beam-type RATS. 



52 




FIGURE 7. - Dual-boom angle bolter with beam-type RATS. 




FIGURE 8. - Single-boom roof bolter with beam-type RATS. 



53 





FIGURE 9. - Lightweight temporary roof support jack. 



.*» 




£:i 



FIGURE 10. - Mobile roof support (MRS) prototype machine. 



54 



The other project called for the de- 
sign, construction, and test of a mobile 
roof support (MRS) , as shown in figure 
10. This machine was tested underground 
at Inland Steel's Sesser Mine in Illi- 
nois. The four hydraulic jacks mounted 
on the battery-powered chassis are each 



capable of supporting 30 tons. There 
were a few problems with the prototype, 
but a second generation MRS has been 
built in conjunction with the Bureau of 
Mines and Southern Utah Fuel Co. Tests 
have not been completed. 



55 



ROOF SUPPORT SYSTEMS FOR FLETCHER ROOF DRILLS 
By Douglas R. Hardman 1 



INTRODUCTION 



The first automated temporary roof sup- 
port system (ATRS) for a roof bolting ma- 
chine was developed by J. H. Fletcher & 
Co. in mid-1971 and was delivered to a 
mine in November 1971. In 1972, a system 
was exhibited at the coal show in Cleve- 
land, and several retrofit kits were de- 
veloped. Since about mid-1973 most of 
our dual-head roof bolters have had a 
roof support system of some type. 

Although we have some standard mod- 
els of equipment, we also make custom- 
designed machines; therefore, we have 
several different ATRS configurations. 
While we have built a few ATRS systems 
that are attached to and move with the 
drilling unit, our main thrust has been 
toward systems that are independent of 
the drilling boom. This allows us to 
keep the worker under supported roof 
while maneuvering the drill head from 



the drilling controls. This paper cov- 
ers roof supports on our different stan- 
dard machines, custom-designed systems, 
single-head systems, and retrofits. 

All of the roof support systems dis- 
cussed in this paper conform to the West 
Virginia regulations for ATRS systems, 
but this does not necessarily mean they 
will comply with every mine roof support 
plan approved by MSHA. When a machine 
with a new ATRS is put into service, the 
mine operator must file a request for 
change to the roof support plan with 
MSHA. Over the past 10 to 12 yr we have 
worked very closely with roof support 
people at MSHA Technical Support and 
the local MSHA representatives. In all 
cases, their help and input have proved 
invaluable, and we have never had any 
problems in working out a viable 
solution. 



TYPES OF FLETCHER ATRS SYSTEMS 



Most of the machines we build are 
dual head, for which we have three main 
types of TRS systems: the H-style, the 
T-style, and the scissors style. The 
H-style, shown in figure 1, is used on 
our model DDM machines and is designed to 
elastically support a maximum load of 
67,500 lb. The purpose of this type of 
system is to allow the operator to in- 
stall two rows of bolts without having to 
reposition the machine. 

The T-style TRS is shown in figure 2. 
This type of roof support is used on most 
of our dual-head machines with various 
mounting configurations, depending on the 
model of machine, mine conditions, and 
working height. Most of these T-style 
units sump and tilt to allow for a more 

1 Manager, Engineering Services, J. H. 
Fletcher & Co., Huntington, WV. 



compact package when tramming from place 
to place. These sump and tilt functions, 
along with features like front end lift 
and wagon brakes, are controlled from 
the inch-tram area as well as the tram 
deck. 



Contact pads 



ATRS support 
member assembly 



TRS support frame 




Outer boom 



Inner boom 



FIGURE 1.- H-style ATRS. 



56 



The scissors TRS shown in figure 3 is a 
variation of the T-style and was devel- 
oped to gain increased versatility in 
low-seam operations. This system will 
collapse to a height of 30 in with 6 in 
of underclearance and extend to a maxi- 
mum height of 8 ft if the need arises. A 
version of the scissors has also been 
built that will collapse to 24 in with a 
60-in extension for operation in 29- to 
30-in conditions. This type of system is 
best suited for mining heights below 4 
ft. The 8-ft maximum height allows for 
excellent flexibility when conditions 
vary, but as the beam goes higher, the 
mechanics of the linkage cause it to rise 
at a slower rate. 



ATRS beam assembly 



Safety post assembly 




ATRS tilt cylinder 
ATRS frame assembly 



ATRS skid foot assembly 

FIGURE 2. - T-style ATRS. 



It also should be noted that the beam 
rises in an arc, which necessitates sump- 
ing the ATRS in and out for varying roof 
conditions. The beam and support struc- 
ture for the T and scissors roof supports 
are designed to elastically support a 
load of 38,250 lb at a maximum width of 
12 ft. 

Most of our ATRS systems are supplied 
with adjustable rocker pads which allow 
the width of the support envelope to be 
varied in 6-in increments from 8 to 10 ft 
on one model and from 10 to 12 ft on 
another. All of these roof supports are 
actuated by hydraulic cylinders equipped 
with integral pilot-operated check valves 
which have a design pressure rating of 
10,000 psi. The schematic in figure 4 
shows that the circuit is designed to 
maintain thrust against the roof. When 
the control valve section is actuated to 
extend, the cylinder flow is directed to 
the V2 port in the relief and check valve 
package. A built-in relief valve on the 
up-stroke side of the circuit allows the 
pressure setting on the system to be al- 
tered. Downstream from the relief valve 
there is a pilot-operated check valve in 
the line which acts to keep the accumula- 
tor charged. The accumulator usually has 
a capacity of 1 gal and is in the cir- 
cuit to provide makeup oil to the system, 
which helps offset things like settling 



Tension link assembly 






ATRS bar assembly 




Lift cylinder 



Compression link 

FIGURE 3. - Scissors support system. 



Foot assembly 



57 



Check and relief 
valve package 



-& 



Roof support 
cylinder 

c 



s> 



-fc- 

/ / 



) 



ACC ,h L 



Accumulator 



C 



IV, 



Control 
valve section 



,JL 



1 



$ 



1 



-~^J,800ps 



FIGURE 4. - Schematic of ATRS hydraulic system. 



of the foot into the floor and minor main hydraulic tank. This lets oil out 



leakage at the cylinder. In the package 
valve the return side of the cylinder is 
connected, through an orifice, to the 



of the top of the cylinder when it is 
trying to readjust due to accumulator 
pressure. 



DUAL-HEAD ROOF BOLTER MODELS 



One of the standard dual-head machines 
built by Fletcher is the model DDM (figs. 
5-6), which uses the H-style ATRS. This 
system allows the operator to install two 
rows of bolts with one machine setup. 
This is made possible by mounting the 
drill unit on a boom that swings 7 ft 
from the machine center line and sumps 
forward 9 ft. It is also possible to in- 
stall a third row of bolts when the inby 
cross beam is within 5 ft of the face. 

The ATRS controls for this machine are 
located in the tram deck along with con- 
trols for brakes, stab jacks, and boom 
swing. It should also be noted that each 
drilling unit is equipped with a safety 
post that can be considered part of the 
roof control system in some cases. Fig- 
ure 6 shows an example of a special DDM 
with offset drilling units which was 
designed to provide operator protection 
in mines where bad rib conditions are a 
major concern. Machines of this type 
have been operating very effectively for 
years. 

Figures 7 and 8 show two versions of a 
model DDO machine. There are quite a few 
different variations of this model, rang- 
ing from machines that will work in seam 
heights of 30 in to units that will 



operate in 8 ft of coal. All of these 
machines either use a T (fig. 7) or scis- 
sors (fig. 8) ATRS, depending on the 
height and operating conditions. The 
drill booms swing 9 ft from center and 
are equipped with 12-, 18-, or 24-in 
sumps. The positioning and ATRS controls 
are located over the left front wheel, 
and the unit must be moved after each row 
of bolts. In most cases a canopy is pro- 
vided over the drill controls, but in 
some instances the canopy support cylin- 
ders have been approved as safety posts 
in lieu of canopies. In either case, as 
the operator moves from hole to hole in- 
stalling a row of bolts parallel to the 
face, the main roof support system re- 
mains in place. 

The DDR (fig. 9) is a relatively new 
model developed for areas where a mast- 
feed type of machine was requested. Dif- 
ferent versions of this machine will op- 
erate in seam heights ranging from 5 to 
12 ft. This model uses a T-style ATRS 
and in most cases incorporates either a 
canopy or a safety post at the drilling 
controls. The positioning and ATRS con- 
trols are located at the left front 
wheel, and the sequence of operation is 
the same as for model DDO. 






58 




FIGURE 5. - Standard model DDM. 




FIGURE 6. - Model DDM with offset drill controls. 



59 





IGURE 7. - Model DDO with T-style ATRS. 




m 



£ 



FIGURE 8. - Model DDO with scissors-style ATRS. 



60 




FIGURE 9.- Model DDR. 




FIGURE 10. - Model HDDR with inside controls. 



61 



The model HDDR shown in figure 10 is an 
example of a very versatile machine de- 
signed for mines with high coal and bad 
rib conditions. This machine can install 
angle bolts and rib bolts as well as a 
conventional pattern. The drilling con- 
trols are in a basket that rises and 
moves with the drilling unit. The opera- 
tor is under a canopy and is protected 
from rib falls by the boom structure. 
Figure 10 shows that the inch-tram and 
ATRS controls are located at the front of 
the machine and are accessible from ei- 
ther operator basket. In this situation 
the operator is not always under bolted 
roof when setting the ATRS but is under a 
canopy. Because of the bad rib condi- 
tions MSHA has approved this system, and 
we have several in operation in the West- 
ern States. These machines all have 
T-style ATRS systems which will operate 
in seam heights from 6 to 16 ft. 

A new version of the DDR has just been 
developed to try a new approach to the 
problem of accessing inside controls. In 
this case there is a walkway through the 
middle of the machine which allows easy 
access to the front end and the inch-tram 
controls located behind the ATRS mounting 
point on the chassis. 

At present Fletcher builds two models 
of dual-head machines that are primarily 
used to drill holes on an angle and in- 
stall trusses. The DDJ shown in figure 
11 uses a T-style ATRS in conjunction 
with canopies or safety posts near the 
drilling controls. The positioning and 
ATRS controls are located at the left 
front wheel along with controls for front 
and rear lift and wagon brakes. The 
drilling units and controls on this model 
move in a straight line parallel to the 
face, and one complete row of bolts may 
be installed with each machine setup. 
The DDJ can be designed for seam heights 
of 4 to 8 ft. 

The LDDR shown in figure 12 is a rela- 
tively new design and is more versatile 
than the DDJ in that the booms sump and 
there is an extra swing function. This 
model uses a T- or scissors-style ATRS, 



and the chassis configuration is very 
similar to that of the DDJ and DDO. This 
model also utilizes a canopy or a safety 
post at the drill controls, and the se- 
quence of operations is the same as for 
the other models with the T or scissors 
ATRS. A floating tram cab like the one 
on the LDDR in figure 12 is optional on 
all our dual-head bolters to allow for 
greater operator headroom in lower seams. 

As can be seen from the previous dis- 
cussion, the configuration of the drill- 
ing units on our dual-head machines var- 
ies drastically, but the roof support 
systems and the operating sequences are 
very similar on every model except the 
DDM and HDDR. The machine is trammed in- 
to the working place from the tram deck, 
which is located at the rear of the unit 
and covered by an approved canopy. The 
operator then actuates a diversion valve 
which shifts the flow of oil to the posi- 
tioning or inch-tram controls. This pre- 
vents accidental actuation of the tram 
controls when the operator is at the 
front of the machine. The operator then 
proceeds to the positioning station and 
moves the machine into final position for 
installing the first row of bolts. It 
should be noted that at this point the 
operator is still under bolted roof. At 
this time the operator sets the ATRS, 
throws another diversion valve which 
sends the flow of oil to the drilling 
controls, and moves forward to position 
the drill head and install the first 
bolt. 

The drilling unit swings at least 9 ft 
and sumps at least 12 in, which allows 
the operator to precisely pinpoint each 
bolt location in the row without disturb- 
ing the roof support system. For special 
bolt patterns the sump and swing may be 
increased and the width of the roof sup- 
port system varied accordingly. 

Retrofit of ATRS systems to Fletcher 
dual-head machines is not a major prob- 
lem, and at this time most of the models 
built without roof supports have had sys- 
tems designed for them. The principle is 
the same as already discussed for most 



! I 



62 



;.,..:,:. I-V^T 'V*X'*.,-:.Ti^,: 4 ,.j 




FIGURE 11. - Model DDJ with T-style ATRS. 




FIGURE 12. - Model LDDR with scissors-style ATRS and floating tram cab. 



63 



models; in most cases the only problem 
has been developing mounting brackets for 
some of the custom-designed units built 
in the late 1960's. As was stated in the 
beginning of this paper, almost all dual- 
head machines built since mid-1973 were 
shipped with a roof support system of 
some type. 

Although our main thrust is to iso- 
late the ATRS from the drilling unit, we 
have built a few units with other sys- 
tems. Figure 13 shows a DDM with a 
crows-foot roof support. On this unit no 
inch tram is required because the boom 
will sump 9 ft. A valve was mounted on 
the boom about 5 ft behind the drillng 
controls; from this point, the operator 
controls the roof suport and repositions 



the drilling unit 
bolted roof. 



while remaining under 



Figure 14 shows a DDO with a ring-style 
ATRS. Both of these types of roof sup- 
ports conform to the law, but there are 
two major problems. First, it is very 
hard to position the drillhead with any 
degree of accuracy, and often it takes 
more than one try, which can be time con- 
suming in a production cycle. Second, 
and most important, is the fact that when 
the boom is being moved there is no sup- 
port at all in contact with the roof. 
The beam system is always in contact with 
the roof when the man is at the drilling 
controls , and this extra edge has proved 
to be valuable. 



SINGLE-HEAD ROOF BOLTER MODELS 



For our single-head machines we have 
two types of ATRS systems — the crows foot 
and the arm style with rocker pads. Fig- 
ure 15 shows a crows foot roof support in 
relation to the drill head on a mast feed 
style machine, and figure 16 shows a lay- 
out of a crows foot with a ring. The 
configuration of this type of system var- 
ies depending on the machine model, the 
mine roof conditions, and customer input. 
The design load rating depends on the 
support envelope, but in most cases it 
works out to around 11,250 lb. If this 
type of support is used in lieu of cano- 
pies, the arms must project at least 18 
in in front of the drill head. The crows 
foot is mounted on either a single or 
double extending cylinder enclosed in a 
shroud of telescoping square tubing, and 
the hydraulic circuit is the same as 
shown in figure 4. As mentioned before, 
this system is attached to and moves with 
the drill unit, which can cause problems. 

The arm-type system of roof support is 
used on our new model LTDO shown in fig- 
ure 17. The arms move independently of 
each other and are tied together only in 
that the two hydraulic cylinders are op- 
erated by the same valve section. This 
feature, along with the rocker pads, al- 
lows for maximum surface contact in un- 
even roof. This system will also work 



with a ring, but some degree of flexibil- 
ity will be sacrificed by tying the arms 
together. In almost all cases, both the 
arm-style and the crows-foot roof sup- 
ports are made of a high-strength alloy 
steel with a minimum yield of 100,000 
psi to achieve a reasonable weight-to- 
strength ratio. The drilling unit of the 
LTDO is independent of the arms , and it 
is able to sump 8 in and swing 3 in to 
each side of center. This feature allows 
for accurate bolt location without dis- 
turbing the roof support. The LTDO in 
figure 18 also has a canopy incorporated 
into the rocker of the ATRS. 

The model DB machine is different from 
the LTDO only in that it uses a mast feed 
for the drill head instead of an arm 
feed and a crows-foot rather than an arm- 
type ATRS. Both the LTDO and DB have the 
inch-tram and ATRS controls between the 
wheels and a tram deck with canopy at the 
rear of the machine. In both cases, ei- 
ther a stab jack or stab foot is included 
and is considered a part of the support 
system. A floating tram cab for low 
seams is also available on model LTDO 
and DB machines. 

To date, we have not built a single- 
head machine that can install more than 
one bolt on a regular pattern with a 



64 




FIGURE 13. - Model DDM with crows-foot ATRS. 




FIGURE 14. - Model DDO with ring-style ATRS. 



65 



Crows foot ATRS 




Drillhead 



FIGURE 15. - Crows-foot ATRS on drill mast. 



single ATRS setup; however, we have de- 
signed a few single-head machines that 
could do this. In most cases a dual-head 
machine is much more practical from a 
cost benefit standpoint than a single- 
head unit, and for this reason, we have 
not emphasized the single-head, multiple- 
bolt machine. 

Retrofit kits have been developed for 
most of our single-head units using ei- 
ther a crows-foot or an arm-style ATRS. 
Since most of these old machines do not 
have swinging or sumping booms , the roof 
support and the drill head are usually 
not independent of each other. Another 
factor that must be taken into considera- 
tion on older machines is tram canopies. 
Most of these machines did not have tram 
decks at the rear when they were origi- 
nally built, so a tram canopy must be 
added to comply with MSHA requirements 
when they are modified. Fletcher has de- 
veloped a few kits for some of our LTDO's 



Ring assembly 



Snubber 30321 pin 



mffim 



o oi 
o oi 



i o o 

'o o 



SECTION A-A' 




Z Z Z jfl 



1 mi 

- t -n - iinl 

— -U. JU —it™ 

r- 1 — i inn 

i_ i_ .in 

_q_ _i i 
i mi 



i 



ELEVATION 

FIGURE 16. - Crows-foot ATRS with ring. 





66 




FIGURE 17. - Model LTDO with arm-style ATRS. 




FIGURE 18. - Model LTDO with drilling canopy on ATRS rocker pad, 



67 




FIGURE 19. - Model DB with retrofitted crows-foot ATRS. 




FIGURE 20. - Stand-alone or satellite ATRS system on a model DO. 



68 



and DB's, but the cost and time involved 
were excessive and in the end we had a 
machine that was too cumbersome to be 
practical in a production cycle. It also 
should be remembered that most of the 
frames and drive systems on these old 
units were not designed to carry the 
increased weight encountered when adding 
a roof support and tram deck. A crows- 
foot ATRS can be added fairly easily to 
a machine that already has a rear tram 
deck, but reduced flexibility makes it 
very hard to use a machine of this type 
in a production cycle. Figure 19 is an 



example of a retrofit of a crows foot on 
a model DB drill. 

We tried a stand-alone, or satellite, 
ATRS system on a single-head model DO 
roof drill (fig. 20) in 1973 but set the 
concept aside because we felt that the 
possibilty of knocking the support posts 
out with the machine was too great. The 
ATRS unit contained two cross members; 
unlike satellite systems developed by 
others, our ATRS was carried with a pair 
of extra lifting arms instead of the 
drill head. 



RETROFIT AND REBUILD PROCEDURES 



After careful consideration and some 
cost studies of existing retrofit proj- 
ects, we feel that in many cases the 
most practical thing to do is salvage the 
parts and install them on a new chassis, 
with a rear tram deck and an arm-style 
ATRS. Many of the components such as 
wheel hubs , drive motors , drill heads , 
and valves can be reused, and in most 
cases all of the cylinders and electrical 
components will adapt. In all cases a 
new chassis would be designed to adapt to 
as many of the old components as pos- 
sible, and the drill unit would be in- 
stalled on a boom that swings and sumps. 
We feel that this can be done for a rela- 
tively small additional cost, and in the 



end the customer will have a machine that 
Is much more practical from a production 
standpoint. Increased productivity could 
very well offset the increased cost of 
the new chassis and boom. 

This may not be the best solution, how- 
ever, if the machine is going to be used 
only for utility bolting. Since the lo- 
cation of the bolt will not be critical, 
a crows-foot kit or a good canopy may be 
the best solution. Each situation must 
be studied, and the best solution will 
depend on how the machine is going to be 
used, the conditions in which it will be 
required to operate, and the overall con- 
dition of the machine in question. 



69 



ATRS SYSTEMS FOR LEE-NORSE ROOF BOLTERS 
By Guido Bucelluni 1 



INTRODUCTION 



Several of the papers presented ear- 
lier in this meeting discussed the tech- 
nical aspects of ATRS systems in general 
and the requirements of existing ATRS 



regulations. Therefore, this paper will 
discuss only Lee-Norse bolting machines 
and the ATRS systems designed for them. 



GENERAL FEATURES 



All ring-type or support-arm ATRS sys- 
tems for Lee-Norse bolters contain all 
design features needed to meet ATRS and 
"in lieu of canopy" regulations (pilot 
check valves, streamlined controls, load- 
carrying capability, etc.). The config- 
uration of the roof support ring on Lee- 
Norse bolters can vary from round to 
hexagonal to rectangular, but all such 
structures extend 6 in inby the drill 
chuck. The support arm hydraulic system 
is designed to automatically maintain a 
factory-determined upward thrust of 1,500 
to 2,000 lb on the roof support struc- 
ture. Most Lee-Norse bolter models con- 
tain a sumping drill box (8-in range of 
travel) to compensate for drill chuck 
misalignment when the support arm is in 
place. This feature allows the operator 
to locate the drill hole precisely with- 
out moving the entire ATRS system. All 



design features of the support-arm system 
can be retrofitted to machines in the 
field. 

Although the support arm ATRS system 
alone is sufficient to meet all ATRS re- 
quirements, some customers also desire 
the additional protection of an out- 
front, bar-type ATRS structure. For this 
reason, Lee-Norse offers two types of 
bar-type structures, the dolly-bar and 
the T-bar designs, as optional or retro- 
fit equipment on all dual-head bolters. 
The dolly bar has a collapsed height of 
23 in and requires 4 to 7 s to reach its 
maximum extended height of 93 in. The 
T-bar has a more limited height range (51 
in to 10 ft) , but has a sump range of 54 
in. When the sumping jack is fully re- 
tracted, the T-bar fits easily between 
the support arms of the dual-boom bolter. 



SINGLE-HEAD BOLTERS 



Figure 1 shows the TD 1-24/ 2 7 model roof 
bolter (frame height 24 to 27 in), and 
figure 2 shows the TD1-29/31 model (frame 
height 29 to 31 in). Both models contain 
support-arm ATRS systems with streamlined 
inch-tram stations. One major difference 
between the two models is that the 



1 Product manager, roof bolters, 
Norse Co., Pittsburgh, PA. 



Lee- 



TD1-29/31 has a cantilevered, "elephant 
ear" canopy over the drilling-bolting 
station, whereas the TD1-24/27 does not. 
The other major difference is that the 
tramming deck and canopy are located on 
the left rear corner of the TD1-29/31; 
on the TD1-24/27 these items are located 
farther forward, adjacent to the left 
tram wheels. 



70 




FIGURE 1. - Low-coal, single-head, TD1-24/27 roof bolter with safety-arm ATRS. 

DUAL-HEAD BOLTERS 



Lee-Norse manufactures three basic 
models of dual-head roof bolters — the 
TD2-30/34 (figs. 3-4), the TD2-43 (figs. 
5-6), and the TD-12 (fig. 7). Figure 3 
shows the TD2-30/34 with support arms 
only; figure 4 shows the same machine 
with a dolly-bar ATRS system in addition 
to the support arms. Note in figure 3 
that the tramming deck and canopy are lo- 
cated between the tires on the right side 
of the machine. 

The TD2-43 (figs. 5-6) is a slightly 
larger machine (support arms reach 10 ft 
high) , but its tram station is basical- 
ly the same as the one on the TD2-30/ 
34. The major differences between the 
machines in figures 5 and 6 are (1) the 
TD2-43 in figure 5 has round roof support 
rings and a dolly-bar ATRS beam and 



(2) the TD2-43 in figure 6 has rectangu- 
lar roof support rings and a T-bar ATRS 
beam. 

Figure 7 shows the mast-type TD-12 
bolter, designed for situations where an- 
gle bolting is required (roof trusses, 
rib bolts, etc.). When used for vertical 
drilling, the posts and canopies above 
the drilling-bolting stations are suffi- 
cient to meet all applicable regulations; 
the out-front dolly bar is an optional 
feature. Since truss and rib bolts are 
usually installed under supported roof , 
only canopy laws apply, so the TD-12 ma- 
chine is sufficient for this purpose. 
The out-front dolly bar (or T-bar) may be 
required if angle drilling is conducted 
in areas of unsupported roof . 



71 




FIGURE 2. - Single-head TD1-29/31 roof bolter with safety-arm ATRS and cantilevered drilling 
canopy. 



.•■"•""•""""""dfc 




FIGURE 3. - Dual-head TD2-30/34 roof bolter with safety-arm ATRS. 



72 




FIGURE 4. - TD2-30/34 roof bolter with dolly-bar and safety-arm ATRS. 




FIGURE 5. - Dual-head TD2-43 roof bolter with dolly-bar ATRS. 



73 





FIGURE 6. - TD2-43 roof bolter with T=bar ATRS. 




FIGURE 7. - Mast=type TD-12 roof bolter for angle bolting. 



74 



LONG-AIRDOX ATRS SYSTEMS FOR ROOF BOLTERS 
By C. L. Bandy, Jr., 1 and David L. Phillips 2 



INTRODUCTION 



Long-Airdox Co. has been a manufacturer 
of roof bolting machines for over 20 yr. 
In view of this , it is easy to understand 
that Long-Airdox has a vested interest in 
safety systems for roof bolting machines. 
Subsequently, a series of ATRS systems 
have been developed and integrated into 
their product lines. 

Although presently West Virginia and 
Virginia are the only States to mandate 
the use of ATRS systems, Long-Airdox 
feels that such systems used on bolting 
machines are effective tools for protect- 
ing miners during the installation of 
permanent supports. Together with pro- 
viding protection for miners, substantial 
time savings in bolter turnaround time 
have been realized, thus enhancing their 
use. 

'Director, field service training, 
Long-Airdox Co., Oak Hill, WV. 

2 Project engineer, roof bolters, Long- 
Airdox Co., Oak Hill, WV. 



NEW MACHINE DESIGNS 

Long-Airdox Co. offers a wide range of 
roof bolting machines to work in low, 
medium, and high seams. 

LRB-25 For Low Seams 

Figure 1 shows an LRB-25 roof bolter 
designed for low-seam operation. As 
shown, the LRB-25 is equipped with a 
mast-type ATRS with a single-beam load 
frame. The ATRS load certification is 
for 22,500 lb. The ATRS has a hydrauli- 
cally actuated stroke of 12 in with a 
nominal base specified from 22 to 34 in. 
Overall height may be adjusted upward (in 
2-in increments) an additional 6 in. As 
shown in figure 1, the ATRS remains at- 
tached to the bolter and can be raised up 
with 5 in of ground clearance and remain 
22 in in overall height. Once the ATRS 
is set, it acts as a stabilizer, thus 
permitting the bolter to be backed away 
approximately 14 in, allowing clear 




FIGURE 1. ° LRB-25 for low seam with single=beam mast-type ATRS. 



75 



access for installing bent bolts. The 
LRB-25 measures 24 in high (with 4-in 
ground clearance) by 44 in wide by 11 ft 
9 in long and weighs 4,400 lb. 

LRB-15AR For Low to Medium Seams 

Figure 2 shows a model LRB-15AR roof 
bolter equipped with a safety-arm- type 
ATRS. The ATRS ranges from 30 in minimum 
to 76-5/8 in maximum (6-in ground clear- 
ance) and is load certified at 11,250 lb. 
Maximum range is 82-5/8 in with 12-in 
ground clearance. An opening measuring 
21 in wide by 32 in long is provided in 
the ATRS for ease of bolting. The LRB- 
15AR measures 27 in high by 74 in wide by 
14 ft 10 in long (with 6-in ground clear- 
ance) and weighs 12,000 lb. 

LRB-16 for Medium to High Seams 

Figure 3 illustrates the LRB-16 roof 
bolter, which is furnished with a single- 
safety-arm type ATRS. The ATRS ranges 
from 50-1/2 in mimimum to 120 in maximum 
(with 18-in ground clearance) and is load 
certified at 11,250 lb. Minimum range is 



42-1/2 in with 10-in ground clearance. 
An opening is provided in the ATRS head 
measuring 27-1/2 in by 30 in to ease the 
bolting operation. The LRB-16 overall 
dimensions are 50 in high (18-in ground 
clearance) by 80-1/2 in wide by 19 ft 

4 in long, and it weighs 18,200 lb. 

LRB-23 for Medium to High Seams 

Figure 4 pictures a Long-Airdox LRB-23 
dual-arm roof bolting machine with a 
mast- type H-beam load frame ATRS cer- 
tified at 67,500 lb. This model is 
also available with a mast-type ATRS 
with single-beam load frame certified at 
33,750 lb. ATRS range is specified from 
48 in minimum to 14 ft in maximum. 
ATRS width is adjustable from 8 ft in 
to 10 ft in. The ATRS is provided with 
a 7 ft in nominal sump, thus allowing 
for two rows of bolts using standard cen- 
ters. The H-beam ATRS design provides 

5 ft in between load frames. Basic ma- 
chine dimensions for the LRB-23 are 48 in 
high (12 in ground clearance) by 9 ft 2 
in wide by 20 ft 4-3/8 in long. Weight 
is approximately 46,100 lb. 




FIGURE 2. . LRB-15AR with safety-arm ATRS. 



76 




FIGURE 3. - LRB-16 with safety-arm ATRS. 




FIGURE 4. - LRB-23 with mast-type H-beam ATRS. 



RETROFITTING 

Along with designing ATRS systems for 
new roof bolting machines, Long-Airdox 
has an ongoing program of design to fit 
existing units with ATRS systems. Two 
existing Long-Airdox roof bolters (LRB-15 
and LRB-15A) have conversion kits avail- 
able from the factory, as follows: 



LRB-15A conversion to safety-arm-type 
ARTS 

1. Complete inch-tram system. 

2. Relocation of ATRS controls to a 
point where they will be under permanent- 
ly supported roof during setup. 



77 



3. Complete ATRS system as per LRB- 
15AR design (not mandatory if unit was 
equipped from factory with roof support 
system) . 

LRB^15 conversion to mast-type 
H-beam load frame ATRS 



3. Complete inch-tram system. 

4. Unit is fitted with a mast-type 
ATRS. Some units were originally sup- 
plied with a canopy from the factory. If 
so, this canopy is removed and bolter is 
then fitted with ATRS. 



1. Relocation of tram compartment from 
front to rear of unit. 



2. General 
components. 



rearrangement of internal 



5. ATRS controls are located where 
they will be under permanently supported 
roof during setup. 



CONCLUSION 



Since the early 1960's, Long-Airdox has 
been actively engaged in the design of 
roof bolting machines. Functional ATRS 



systems have evolved and been accepted as 
viable protective devices for mine per- 
sonnel during the bolting operation. 



aU.S. CPO: 1984-505-019/5081* 



INT.-BU.OF MINES, PGH., PA. 27752 



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